PERF: Improve Styler to_excel Performance

[tehunter]

• closes PERF: Excel Styler treatment of CSS side expansion is slow #47352
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

[pep8speaks]

Hello @tehunter! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2022-06-29 14:18:30 UTC

[tehunter]

ASV Results:

..       before           after         ratio
     [6f0be79b]       [db365209]
                      <styler-performance>
-       915±200ms         594±30ms     0.65  io.excel.WriteExcel.time_write_excel('openpyxl')
-       658±200ms         323±20ms     0.49  io.excel.WriteExcel.time_write_excel('xlsxwriter')
-       3.08±0.1s         934±40ms     0.30  io.excel.WriteExcelStyled.time_write_excel_style('xlsxwriter')

SOME BENCHMARKS HAVE CHANGED SIGNIFICANTLY.
PERFORMANCE INCREASED.

[tehunter]

@github-actions pre-commit

[tehunter]

Overview of changes:

• Moved CSSResolver.expand_* methods (which are accessed in .atomize) to a dictionary called CSS_EXPANSIONS which is keyed directly by the CSS property, instead of having to do a string replace and concatenation.
• CSSResolver.__call__ now accepts an iterable of declaration tuples (property, value) in addition to the previous string type.
  • When an iterable is passed, .parse does not need to be called
• CSSExcelCell.__init__ no longer converts the css_styles (i.e. Styler.ctx) from a list of tuples to a CSS string. Instead, the list is converted to a frozenset via a dictionary (to keep only the final instance of each property declaration)
  • The list of tuples was already obtained from the initial CSS string(s) in Styler._update_ctx, so we were previously parsing, reforming into string, and parsing again.
• CSSToExcelConverter.__call__ is now cached using lru_cache. The frozenset was necessary to make all the arguments hashable for the caching mechanism.

[tehunter]

Benchmarks as of 8e56402

.       before           after         ratio
     [2b1184dd]       [8e56402e]
                      <styler-performance>
-        260±10ms          233±5ms     0.90  io.excel.WriteExcel.time_write_excel('xlsxwriter')
-        620±70ms         450±20ms     0.73  io.excel.WriteExcel.time_write_excel('openpyxl')
-      2.51±0.02s        1.42±0.3s     0.57  io.excel.WriteExcelStyled.time_write_excel_style('openpyxl')
-      1.69±0.07s         608±10ms     0.36  io.excel.WriteExcelStyled.time_write_excel_style('xlsxwriter')
- ```

[mroeschke]

Awesome improvement! Thanks @tehunter