[Debugify] Add 'acceptance-test' mode for the debugify report script (#147574)

For the purposes of setting up CI that makes use of debugify, this patch
adds an alternative mode for the llvm-original-di-preservation.py
script, which produces terminal-friendly(-ish) YAML output instead of an
HTML report, and sets the return code to 1 if the input file contains
errors, or 0 if the input file contains no errors or does not exist,
making it simple to use it in CI.

This introduces a small change in existing usage, in that the path for
the HTML report file is now passed with `--report-file <path>` rather
than as a positional argument; I could make the argparse logic work
without this change, but I believe that is simpler to understand this
way, and to my knowledge debugify isn't currently being used in
automated environments where changing this might cause issues. As a
small change while passing by, I also changed `-compress` to
`--compress`, for consistency.

As a note for reviewers, the reason that we treat a non-existent input
file as a pass is that this is actually the expected state: we use clang
to compile numerous files, passing a filepath for debugify errors. Any
errors found by debugify will be written to this file; if none are
found, the file is untouched. This is also mentioned in a code comment,
but I think it useful to state upfront.

Finally, the justification for adding a new mode to this script instead
of adding a separate script for the separate functionality is that this
script understands debugify's output, and performs some deduplication
that is useful for clarifying the resulting output. Writing a new script
would require duplicating logic unnecessarily, and risks the scripts
falling out-of-sync if changes are made to debugify's output.