Enable sort=True for Index.union, Index.difference and Index.intersection

[galipremsagar]

Description

This PR enables sort=True for union, difference, and intersection APIs in Index.

This also fixes 1 pytest failure and adds 77 pytests:
On Index_sort_2.0:

= 230 failed, 95836 passed, 2045 skipped, 768 xfailed, 308 xpassed in 438.88s (0:07:18) =

On pandas_2.0_feature_branch:

= 231 failed, 95767 passed, 2045 skipped, 764 xfailed, 300 xpassed in 432.59s (0:07:12) =

xref: pandas-dev/pandas#25151

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.