[SPIRV] Implement handle_fromBinding intrinsic. (#111052)

Implement the intrinsic `llvm.spv.handle.fromBinding`, which returns the
handle for a global resource. This involves creating a global variable
that matches the return-type, set, and binding in the call, and
returning the handle to that resource.

This commit implements the scalar version. It does not handle arrays of
resources yet. It also does not handle storage buffers yet. We do not
have the type for the storage buffers designed yet.

Part of #81036