Added support of simple logical ops: `LogicalAnd`, `LogicalOr`,
`LogicalEqual` and `LogicalNotEqual`. Added a missing conversion
for `UMod` op.
Also, implemented SPIR-V cast ops conversion. There are 4 simple
case where there is a clear equivalent in LLVM (e.g. `ConvertFToS`
is `fptosi`). For `FConvert`, `SConvert` and `UConvert` we
distinguish between truncation and extension based on the bit
width of the operand.
Differential Revision: https://reviews.llvm.org/D81812
771b788687