Add option to dump IR to files instead of stderr (#66412)

This patch adds a flag to LLVM such that the output generated by the
`-print-(before|after|all)`
family of flags is written to files in a directory rather than to
stderr.

This new flag is `-ir-dump-directory` and is used to specify where to
write the files. No other flags are added, it just modifies the behavior
of the print flags.

This is a second simplified version of the changes proposed in
https://github.com/llvm/llvm-project/pull/65179

.

This patch only adds support for the new pass manager. If this patch is
accepted, similar support can be added to the legacy pass manager.

Co-authored-by: Nuri Amari <nuriamari@fb.com>