DEPR: deprecate (Sparse)Series.from_array
Closes #18213. 

It's a bit annoying that I have to keep it as internal method. On the other hand this might signal that `from_array` actually has some use case ..
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18258?src=pr&el=h1) Report
> :exclamation: No coverage uploaded for pull request base (`master@7b5ca80`). [Click here to learn what that means](https://docs.codecov.io/docs/error-reference#section-missing-base-commit).
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18258/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/18258?src=pr&el=tree)

```diff
@@            Coverage Diff            @@
##             master   #18258   +/-   ##
=========================================
  Coverage          ?   91.38%           
=========================================
  Files             ?      164           
  Lines             ?    49892           
  Branches          ?        0           
=========================================
  Hits              ?    45594           
  Misses            ?     4298           
  Partials          ?        0
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.19% <100%> (?)` | |
| #single | `39.42% <50%> (?)` | |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18258?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/18258?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.8% <100%> (ø)` | |
| [pandas/core/series.py](https://codecov.io/gh/pandas-dev/pandas/pull/18258?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc2VyaWVzLnB5) | `95.02% <100%> (ø)` | |
| [pandas/core/sparse/series.py](https://codecov.io/gh/pandas-dev/pandas/pull/18258?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3BhcnNlL3Nlcmllcy5weQ==) | `95.33% <100%> (ø)` | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18258?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/18258?src=pr&el=footer). Last update [7b5ca80...4317073](https://codecov.io/gh/pandas-dev/pandas/pull/18258?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/18258?src=pr&el=h1) Report
> :exclamation: No coverage uploaded for pull request base (`master@7b5ca80`). [Click here to learn what that means](https://docs.codecov.io/docs/error-reference#section-missing-base-commit).
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18258/graphs/tree.svg?width=650&src=pr&token=eZ4WkYLtcO&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/18258?src=pr&el=tree)

```diff
@@            Coverage Diff            @@
##             master   #18258   +/-   ##
=========================================
  Coverage          ?   91.38%           
=========================================
  Files             ?      164           
  Lines             ?    49888           
  Branches          ?        0           
=========================================
  Hits              ?    45591           
  Misses            ?     4297           
  Partials          ?        0
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.19% <100%> (?)` | |
| #single | `39.42% <63.63%> (?)` | |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18258?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/18258?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.8% <100%> (ø)` | |
| [pandas/core/series.py](https://codecov.io/gh/pandas-dev/pandas/pull/18258?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc2VyaWVzLnB5) | `95.02% <100%> (ø)` | |
| [pandas/core/sparse/series.py](https://codecov.io/gh/pandas-dev/pandas/pull/18258?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3BhcnNlL3Nlcmllcy5weQ==) | `95.33% <100%> (ø)` | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18258?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/18258?src=pr&el=footer). Last update [7b5ca80...4317073](https://codecov.io/gh/pandas-dev/pandas/pull/18258?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks! @jorisvandenbossche @jreback : This commit introduced the first (and only) instance of `pytest.warns` instead of our in-house `tm.assert_produces_warning`.  Do we have a preference for which should be used now that we require `pytest >= 3.1` ? @gfyoung let's just use ``assert_produces_warning``. and alway pls add a lint rule to fail on``pytest.warns``. We could of course change to use ``pytest.warns`` (maybe) but that's a different issue. @jreback : I figured as such.  Thanks for confirming.