BUG: Fix Index constructor with mixed closed Intervals

[jschendel]

• closes BUG: Index constructor raises for a list of mixed closed Interval objects #27172
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

Note that this solution uses the same pattern that's used to support a list of mixed frequency Period objects:

pandas/pandas/core/indexes/base.py

Lines 444 to 448 in 527e714

	elif inferred == 'period':
	try:
	return PeriodIndex(subarr, name=name, **kwargs)
	except IncompatibleFrequency:
	pass

[jreback]

lgtm merge one green

[jreback]

thanks @jschendel