BLD: prevent asv from calling sys.stdin.close() by using different launch method
This should fix the `asv dev` errors seen in #24953, though this may add a lot of runtime overhead so input on approaches appreciated.

When running `asv dev`, the default `--launch-method=fork` calls `sys.stdin.close()` in the main process where all benchmarks run. The function `DataFrame._repr_html_()` attempts to import `IPython`, which itself attempts a call on `sys.stdin` as part of `IPython.__init__`, which fails due to it having been closed by `asv`. This leads to the following output:
```
[ 30.00%] ··· frame_methods.Repr.time_html_repr_trunc_mi                                                                                                                                              failed
[ 30.00%] ···· Traceback (most recent call last):
                 File "/home/chris/code/asv/asv/benchmark.py", line 1170, in main_run_server
                   main_run(run_args)
                 File "/home/chris/code/asv/asv/benchmark.py", line 1044, in main_run
                   result = benchmark.do_run()
                 File "/home/chris/code/asv/asv/benchmark.py", line 523, in do_run
                   return self.run(*self._current_params)
                 File "/home/chris/code/asv/asv/benchmark.py", line 617, in run
                   min_run_count=self.min_run_count)
                 File "/home/chris/code/asv/asv/benchmark.py", line 680, in benchmark_timing
                   timing = timer.timeit(number)
                 File "/home/chris/anaconda3/lib/python3.7/timeit.py", line 176, in timeit
                   timing = self.inner(it, self.timer)
                 File "<timeit-src>", line 6, in inner
                 File "/home/chris/code/pandas/asv_bench/benchmarks/frame_methods.py", line 226, in time_html_repr_trunc_mi
                   self.df3._repr_html_()
                 File "/home/chris/code/pandas/pandas/core/frame.py", line 652, in _repr_html_
                   import IPython
                 File "/home/chris/anaconda3/lib/python3.7/site-packages/IPython/__init__.py", line 55, in <module>
                   from .terminal.embed import embed
                 File "/home/chris/anaconda3/lib/python3.7/site-packages/IPython/terminal/embed.py", line 16, in <module>
                   from IPython.terminal.interactiveshell import TerminalInteractiveShell
                 File "/home/chris/anaconda3/lib/python3.7/site-packages/IPython/terminal/interactiveshell.py", line 81, in <module>
                   if not _stream or not hasattr(_stream, 'isatty') or not _stream.isatty():
               ValueError: I/O operation on closed file
```
Long term, this needs to be changed upstream in `asv`. Short term, I see a couple options:
 * Disable these benchmarks
 * Use a different launchmethod that does not trigger the `sys.stdin.close()` call

This PR implements the latter by using the `--launch-method=spawn`, but it's to be seen how much overhead that introduces.

The command `asv dev` is shorthand for `asv run --quick --show-stderr --python=same`. Unfortunately, the `asv dev` command does not expose the `--launch-method` flag, so we have to substitute with the extended form.

- [ ] closes #25235
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

cc @WillAyd 
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25237?src=pr&el=h1) Report
> Merging [#25237](https://codecov.io/gh/pandas-dev/pandas/pull/25237?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/04df22fbeec782f474bcff20480eded04e0d1d82?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25237/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25237?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #25237   +/-   ##
=======================================
  Coverage   91.89%   91.89%           
=======================================
  Files         166      166           
  Lines       52226    52226           
=======================================
  Hits        47993    47993           
  Misses       4233     4233
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.44% <ø> (ø)` | :arrow_up: |
| #single | `42.13% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25237?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25237?src=pr&el=footer). Last update [04df22f...d8e911d](https://codecov.io/gh/pandas-dev/pandas/pull/25237?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25237?src=pr&el=h1) Report
> Merging [#25237](https://codecov.io/gh/pandas-dev/pandas/pull/25237?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/04df22fbeec782f474bcff20480eded04e0d1d82?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25237/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25237?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #25237   +/-   ##
=======================================
  Coverage   91.89%   91.89%           
=======================================
  Files         166      166           
  Lines       52226    52226           
=======================================
  Hits        47993    47993           
  Misses       4233     4233
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.44% <ø> (ø)` | :arrow_up: |
| #single | `42.13% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25237?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25237?src=pr&el=footer). Last update [04df22f...d8e911d](https://codecov.io/gh/pandas-dev/pandas/pull/25237?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks @qwhelan 