[HLSL] Enable parsing half suffix for floating point literals

[llvm-beanz]

HLSL supports the h suffix for floating point literals to denote half types. Clang currently blocks that suffix unless the OpenCL 16-bit type extension is enabled: https://godbolt.org/z/f55547a3z

Acceptance Criteria

Test cases demonstrating parsing of floating point values with the h suffix generating correct half AST types.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Chris B (llvm-beanz)

HLSL supports the `h` suffix for floating point literals to denote half types. Clang currently blocks that suffix unless the OpenCL 16-bit type extension is enabled: https://godbolt.org/z/f55547a3z

Acceptance Criteria

Test cases demonstrating parsing of floating point values with the h suffix generating correct half AST types.