rerun_py.dataframe: Add APIs for using_index_values, fill_latest_at, and filter_is_not_null

[jleibs]

What

• Resolves: Expand python APIs to support new data API concepts #7455
• DNM: requires Dataframe v2: big ol' hindsight-driven refactoring #7683

TODO

• The unit test currently fails with what looks like a bug

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[teh-cmc]

I'll rebase this on top of #7683 -- that should fix that test.

• Dataframe v2: big ol' hindsight-driven refactoring #7683

[teh-cmc]

$ pixi run -e py py-test 2>&1 > /dev/null ; echo $?
0

[teh-cmc]

Suggested change

	The index values returned will be the intersection between the provided values and the
	original index.
	The index values returned will be the intersection between the provided values and the
	original index values.