[feature] UnusedUse - rewrite to use Tokens

UnusedUse - rewrite for use Tokens.
Work in progress

- [X] rewrite to use Tokens
- [X] fix #217
- [X] fix #317
- [X] fix #353
this fixer should at least learn to avoid removing bad things in this case (if ``Foobar`` is not used in this case, it should not remove the use statement for ``Foo``).

either it learns to split them properly, or it ignores such use statements, keeping them all the time to avoid breaking the code (replacing multiple sue statements with several single use statements should indeed be a separate fixer)