Add missing constant propogation folder for Bitwise[Or|And|Xor].
Move previous Bitwise[Or|And] fold implementations to
SPIRVCanonicalization for consistency.
Implement additional folding when lhs == rhs and rhs = 0 for Xor. As
well as, update an Xor testcase to account for this introduced folding.
This helps for readability of lowered code into SPIR-V.
Part of work for #70704
40e2bb5330