[X86] combineBitcastToBoolVector - add XOR + Constant handling, match existing...

[X86] combineBitcastToBoolVector - add XOR + Constant handling, match existing BITCASTs and limit recursion depth

Add XOR + constant handling to allow us to detect NOT patterns.

If a recursive combineBitcastToBoolVector call finds an existing BITCAST node then use that.

As combineBitcastToBoolVector is recursive, ensure we limit the maximum recursion depth.

Fixes #93000