[CLN] cleanup import reverse-dependencies
State: closed

Parts of the code are made more difficult to reason about by depending on `pandas.io.formats`, which has dependencies all over the code.

This PR starts in on this by replacing `import Foo` with `import ABCFoo` where possible.  Along the way it cleans up import order.

Labels:
name: Clean

Comments:
Think this will have any impact on the overall import time? @TomAugspurger do you know where that original issue was?
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/21844?src=pr&el=h1) Report
> Merging [#21844](https://codecov.io/gh/pandas-dev/pandas/pull/21844?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/1dd05ccf56b163dc51786e4f5ce76b279cc0dec3?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `97.91%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/21844/graphs/tree.svg?token=eZ4WkYLtcO&src=pr&width=650&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/21844?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #21844      +/-   ##
==========================================
- Coverage   91.92%   91.92%   -0.01%     
==========================================
  Files         160      160              
  Lines       49916    49906      -10     
==========================================
- Hits        45885    45875      -10     
  Misses       4031     4031
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.3% <97.91%> (-0.01%)` | :arrow_down: |
| #single | `42.11% <44.79%> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/21844?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/21844/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `63.2% <100%> (ø)` | :arrow_up: |
| [pandas/plotting/\_timeseries.py](https://codecov.io/gh/pandas-dev/pandas/pull/21844/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL190aW1lc2VyaWVzLnB5) | `64.94% <100%> (-0.36%)` | :arrow_down: |
| [pandas/io/clipboards.py](https://codecov.io/gh/pandas-dev/pandas/pull/21844/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2NsaXBib2FyZHMucHk=) | `100% <100%> (ø)` | :arrow_up: |
| [pandas/io/formats/csvs.py](https://codecov.io/gh/pandas-dev/pandas/pull/21844/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvY3N2cy5weQ==) | `97.66% <100%> (-0.02%)` | :arrow_down: |
| [pandas/plotting/\_tools.py](https://codecov.io/gh/pandas-dev/pandas/pull/21844/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL190b29scy5weQ==) | `72.62% <100%> (-0.31%)` | :arrow_down: |
| [pandas/io/formats/format.py](https://codecov.io/gh/pandas-dev/pandas/pull/21844/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvZm9ybWF0LnB5) | `98.24% <100%> (-0.01%)` | :arrow_down: |
| [pandas/io/formats/excel.py](https://codecov.io/gh/pandas-dev/pandas/pull/21844/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvZXhjZWwucHk=) | `97.37% <100%> (ø)` | :arrow_up: |
| [pandas/io/pytables.py](https://codecov.io/gh/pandas-dev/pandas/pull/21844/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3B5dGFibGVzLnB5) | `92.48% <100%> (ø)` | :arrow_up: |
| [pandas/io/formats/html.py](https://codecov.io/gh/pandas-dev/pandas/pull/21844/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvaHRtbC5weQ==) | `88.85% <100%> (ø)` | :arrow_up: |
| [pandas/io/sas/sas\_xport.py](https://codecov.io/gh/pandas-dev/pandas/pull/21844/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3Nhcy9zYXNfeHBvcnQucHk=) | `90.27% <100%> (ø)` | :arrow_up: |
| ... and [3 more](https://codecov.io/gh/pandas-dev/pandas/pull/21844/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/21844?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/21844?src=pr&el=footer). Last update [1dd05cc...7d246a3](https://codecov.io/gh/pandas-dev/pandas/pull/21844?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).

thanks @jbrockmendel 

yeah this is almost cosmetic as python optimizes the imports, but it is nicer if can consolidate the imports at the top and avoid importing-chain deps.

if you can contrive a linter to actually conform the import orderings (e.g. _libs, util, compat, core), would be great, but might be tricky.