Reland "[HLSL][RootSignature] Add parsing of filter enum for StaticSampler" (#142441)
This relands https://github.com/llvm/llvm-project/pull/140294.
The initial naming of the enum class Filter and the Filter struct member
causes ambiguity when compiling with gcc.
This change addresses this my renaming `Filter` to `SamplerFilter`.
I have confirmed this builds locally using gcc.
Resolves https://github.com/llvm/llvm-project/issues/126574.