closes #74727: allow entity types to end with a capitalized letter provided they contain a lower-cased letter

containing HAVING comparison nodes where it's used and optional (eg outer join)

* & (bitwise AND),
* | (bitwise OR),
* # (bitwise XOR),
* << (bitwise left shift),
* >> (bitwise right shift)
* % (modulo),
* ^ (power),

allow optional on final relation (rhs only) and in having expression (hence Comparison node gain a 'optional' attribute). Closes #71415

# variable stinfo should hold term (Comparison node) where it's referenced in having clause (var.stinfo.get('having')

# should properly update statement's vargraph