ENH GH11978 access pd.plotting._misc from plot accessor
- [X] closes #11978
- [X] tests added / passed
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [X] whatsnew entry

Allows plot accessors to use plotting functions from `pd.plotting`

- Currently only allows function calls (e.g. `df.plot.scatter_matrix()` but not `df.plot(kind='scatter_matrix')` because the handling of the `kind` keyword is interpreted with plot classes whereas the plotting tools in `pd.plotting` are functions. Should the new plotting methods be hard-coded in? Or the misc tools could be refactored into classes?

- Good tests already exist in `test_misc.py`, but they're not easily parametrizable with the plot accessor case (misc functions have frame/series parameter, plot accessor functions don't). Is it okay to have mostly copy-pasted variations of those test cases in `test_frame.py` and `test_series.py` or should they be tested together some other way?