[MLIR][SPIRVToLLVM] Added conversion for SPIR-V comparison ops

Implemented `FComparePattern` and `IComparePattern` classes
that provide conversion of SPIR-V comparison ops (such as
`spv.FOrdGreaterThanEqual` and others) to LLVM dialect.
Also added tests in `comparison-ops-to-llvm.mlir`.

Differential Revision: https://reviews.llvm.org/D81487