DEPR offsets: rename ‘BY’ to ‘BYE'
xref #55792

Deprecated the alias denoting business year end frequency `'BY’` for offsets in favour of `'BYE'`.
Renamed strings 'BY-DEC', 'BY-JAN', etc. denoting business yearly frequencies with various fiscal quarter ends to 'BYE-DEC', 'BYE-JAN', etc.
@MarcoGorelli, could you please take a look at this PR?