[HLSL] Default and Relaxed Availability Diagnostics (#92704)

Implements HLSL availability diagnostics' default and relaxed mode.

HLSL availability diagnostics emits errors or warning when unavailable
shader APIs are used. Unavailable shader APIs are APIs that are exposed
in HLSL code but are not available in the target shader stage or shader
model version.

In the default mode the compiler emits an error when an unavailable API
is found in a code that is reachable from the shader entry point
function. In the future this check will also extended to exported
library functions (#92073). The relaxed diagnostic mode is the same
except the compiler emits a warning. This mode is enabled by
``-Wno-error=hlsl-availability``.

See HLSL Availability Diagnostics design doc
[here](https://github.com/llvm/llvm-project/blob/main/clang/docs/HLSL/AvailabilityDiagnostics.rst)
for more details.

Fixes #90095