DEPR: Period[B]
- [x] closes #53446 (Replace xxxx with the GitHub issue number)
- [ ] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [x] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

There's a place in the plotting code where we apparently cast to Period, not sure why that would be necessary.  Need to find an alternative before the deprecation is enforced.
+1 on deprecating. What about the other Business offsets? > What about the other Business offsets?

The other business offsets aren't used for Period.  (Confusion about that is common, which is part of why i want to decouple offsets from Period entirely) Thanks @jbrockmendel 