[mlir] Refactor pass crash reproducer generation to be an assembly resource

We currently generate reproducer configurations using a comment placed at
the top of the generated .mlir file. This is kind of hacky given that comments
have no semantic context in the source file and can easily be dropped. This
strategy also wouldn't work if/when we have a bitcode format. This commit
switches to using an external assembly resource, which is verifiable/can
work with a hypothetical bitcode naturally/and removes the awkward processing
from mlir-opt for splicing comments and re-applying command line options. With
the removal of command line munging, this opens up new possibilities for
executing reproducers in memory.

Differential Revision: https://reviews.llvm.org/D126447