[mlir][spirv] Change translation to use spirv.module

Update the SPIRV `mlir-translate` translations to translate to/from
`spirv.module` instead of `builtin.module`. This simplifies the
translation since the code no longer needs to walk the module looking
for a SPIRV module, however it requires passing `-no-implicit-module` to
all the tests.

Reviewed By: antiagainst

Differential Revision: https://reviews.llvm.org/D135819