[SPIR-V] Add cl_khr_kernel_clock / SPV_KHR_shader_clock extension (#92771)

Recognize `cl_khr_kernel_clock` builtins and translate them to
`OpReadClockKHR` instructions. The `Scope` operand is deduced from the
builtin function name.

spirv-val does not pass yet due to OpReadClockKHR only supporting the
valid scopes for Vulkan (Device and Subgroup, but not Workgroup), so
leave validation disabled with a TODO.