MNT: Deprecate unused keywords in utils/data.py

[pllim]

Description

This pull request follows up on #10437 to really deprecate unused keywords. We decided not to issue warning when they are refactored to be no-op keywords in #10437 because that PR is being backported to LTS.

With this patch:

>>> from astropy.utils.data import check_download_cache
>>> check_download_cache(check_hashes=True)
WARNING: AstropyDeprecationWarning: "check_hashes" was deprecated in
version 4.2 and will be removed in a future version.  [warnings]

>>> from astropy.utils.data import import_file_to_cache
>>> import_file_to_cache('https://example.com/', 'README.md', hexdigest='abcdef')
WARNING: AstropyDeprecationWarning: "hexdigest" was deprecated in
version 4.2 and will be removed in a future version.  [warnings]
'/path/to/.astropy/cache/download/url/.../contents'

cc @aarchiba

[pllim]

You can ignore the coverage failure.

[aarchiba]

The diff looks fine.

[pllim]

Just rebased and checked locally that this still works:

>>> from astropy.utils import data                                                              
>>> data.check_download_cache(check_hashes=True)                                                
WARNING: AstropyDeprecationWarning: "check_hashes" was deprecated in version 4.2 and will be removed in a future version.  [warnings]
set()

Given blessing from @aarchiba , I just need an official approval to get this in for 4.2.

[bsipocz]

Thanks @pllim