Is your feature request related to a problem? Please describe.
Metallib is a compiled binary result of MSL code. Instead of requiring even "passthrough" shaders to be compiled at run-time, we should allow the user to pass in precompiled metal binary shader files.

This would be very desirable for precompiled shaders.

Describe the solution you'd like
Add support for metallib passthrough

Describe alternatives you've considered
Not doing it since we already have MSL passthrough.

Additional context
Add any other context or screenshots about the feature request here.