MyPy cleanup and absolute imports in pandas.core.dtypes.common
Starting the conversation towards #14468

There were a couple misplaced annotations below docstrings that were causing mypy to choke when running:

```bash
mypy pandas --ignore-missing-imports
```

A starred import in pandas.core.dtypes.common was responsible for a lot of complaints from mypy. These were being intentionally suppressed by flake8 but I figure it makes sense to clean up and convert into absolute imports
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/21008?src=pr&el=h1) Report
> Merging [#21008](https://codecov.io/gh/pandas-dev/pandas/pull/21008?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/aa3e6833ff6e77aeea88c557e18f7d19278f5a66?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/21008/graphs/tree.svg?src=pr&token=eZ4WkYLtcO&width=650&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/21008?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #21008      +/-   ##
==========================================
- Coverage    91.9%    91.9%   -0.01%     
==========================================
  Files         153      153              
  Lines       49549    49548       -1     
==========================================
- Hits        45539    45538       -1     
  Misses       4010     4010
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.3% <100%> (-0.01%)` | :arrow_down: |
| #single | `41.77% <100%> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/21008?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/arrays/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/21008/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL2Jhc2UucHk=) | `83.95% <ø> (ø)` | :arrow_up: |
| [pandas/core/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/21008/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYmFzZS5weQ==) | `96.83% <ø> (ø)` | :arrow_up: |
| [pandas/core/dtypes/common.py](https://codecov.io/gh/pandas-dev/pandas/pull/21008/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZHR5cGVzL2NvbW1vbi5weQ==) | `94.63% <100%> (-0.02%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/21008?src=pr&el=continue).
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> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/21008?src=pr&el=footer). Last update [aa3e683...60642ed](https://codecov.io/gh/pandas-dev/pandas/pull/21008?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 looks fine. can you rebase just to be sure. merge on green.