Related to clean-up opportunities discussed at #90013.
After these cleanups, the `RelaxAll` parameter from
`createMCObjectStreamer` can be removed as well. As
`createMCObjectStreamer` is a more user-facing API and used by two files
in mlir/, we postpone the cleanup to the future.
DXContainer files resemble traditional object files in that they are
comprised of parts which resemble sections. Adding DXContainer as an
object file format in the MC layer will allow emitting DXContainer
objects through the normal object emission pipeline.
Differential Revision: https://reviews.llvm.org/D127165