[SPIR-V] Fix return type when sampling an image with OpImageSampleExplicitLod (#89252)

This PR fixes parsing of builtins return types in general and fixes
return type when sampling an image with OpImageSampleExplicitLod in
particular.

GitOrigin-RevId: eb989f625ee0e47ffa4343abe11b6afa9f3b2e69
4 files changed