Adding support for pandas dataframes, multindex formatting

[afriedman412]

(partially) #970 • table_pandas adapter code formats properly formats pandas dataframes • can now style table indexes automatically the way headers table headers are styled

[ x] The GitHub pipeline is OK (green), meaning that both pylint (static code analyzer) and black (code formatter) are happy with the changes of this PR.

[ x] A unit test is covering the code added / modified by this PR

[ x] This PR is ready to be merged

[ x] In case of a new feature, docstrings have been added, with also some documentation in the docs/ folder

[ x] A mention of the change is present in CHANGELOG.md

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