[SPIRV] add pre legalization instruction combine (#122839)

- Add the boilerplate to support instcombine in SPIRV
- instcombine length(X-Y) to distance(X,Y)
- switch HLSL's distance intrinsic to no

[SPIRV] add pre legalization instruction combine (#122839)

- Add the boilerplate to support instcombine in SPIRV
- instcombine length(X-Y) to distance(X,Y)
- switch HLSL's distance intrinsic to not special case for SPIRV.
- fixes #122766
- This RFC we were requested to add in the infra for pattern matching:
https://discourse.llvm.org/t/rfc-add-targetbuiltins-for-spirv-to-support-hlsl/83329/13

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[SPIRV] Add Target Builtins using Distance ext as an example (#121598)

- Update pr labeler so new SPIRV files get properly labeled.
- Add distance target builtin to BuiltinsSPIRV.td.
- Update Targ

[SPIRV] Add Target Builtins using Distance ext as an example (#121598)

- Update pr labeler so new SPIRV files get properly labeled.
- Add distance target builtin to BuiltinsSPIRV.td.
- Update TargetBuiltins.h to account for spirv builtins.
- Update clang basic CMakeLists.txt to build spirv builtin tablegen.
- Hook up sema for SPIRV in Sema.h|cpp, SemaSPIRV.h|cpp, and
SemaChecking.cpp.
- Hookup sprv target builtins to SPIR.h|SPIR.cpp target.
- Update GBuiltin.cpp to emit spirv intrinsics when we get the expected
spirv target builtin.

Consensus was reach in this RFC to add both target builtins and pattern
matching:
https://discourse.llvm.org/t/rfc-add-targetbuiltins-for-spirv-to-support-hlsl/83329.

pattern matching will come in a separate pr this one just sets up the
groundwork to do target builtins for spirv.

partially resolves
[#99107](https://github.com/llvm/llvm-project/issues/99107)

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