Support SPV_INTEL_rounded_div_sqrt extension (#3770)
Allow `fdiv` or `sqrt` instructions to be decorated with `FPRoundingMode`.
Spec:
https://github.khronos.org/SPIRV-Registry/extensions/INTEL/SPV_INTEL_rounded_divide_sqrt.html
Original commit:
https://github.com/KhronosGroup/SPIRV-LLVM-Translator/commit/a3937121271c94b
