DEPR: 'A' for yearly frequency and YearEnd in favour of 'Y'
xref #54275, #54061

deprecated string `'A'` for yearly frequency and YearEnd in favour of `'Y'`.

EDIT:
deprecated annual frequencies with various fiscal year ends:` "A-DEC", "A-JAN"`, etc. in favour of `"Y-DEC",  "Y-JAN"`, etc.
> in `offsets.pyx` I think you'll need to generalise this part
> 
> ```
>                 if is_period is False and name == "M":
>                     warnings.warn(
>                         "\'M\' will be deprecated, please use \'ME\' "
>                         "for \'month end\'",
>                         UserWarning,
>                         stacklevel=find_stack_level(),
>                     )
>                     name = "ME"
>                 if is_period is True and name == "ME":
>                     raise ValueError(
>                         r"for Period, please use \'M\' "
>                         "instead of \'ME\'"
>                     )
>                 elif is_period is True and name == "M":
>                     name = "ME"
> ```

Thank you for the comment.  I generalised it by adding a dictionary with frequencies deprecated for offsets.  I deprecated annual frequencies with various fiscal year ends: `"A-DEC", "A-JAN"`, etc. in favour of `"Y-DEC",  "Y-JAN"`, etc., added tests for FutureWarning and notes in v2.2.0. @MarcoGorelli, could you please take a look at this PR? Thank you for helping me with this PR.