Add run_interdiff

[bmastbergen]

This is a wrapper for running interdiff on pr commits that are backports of upstream kernel commits. The calling convention is similar to check_kernel_commits, where you pass the kernel-src-tree repo, the pr branch, and base branch as arguments. The script then looks though each pr commit looking for backported upstream commits, and calls interdiff to check for differences between the referenced upstream commit and the pr commit itself.

As with check_kernel_commits the --markdown argument adds a little flair for embedding the output in a github comment

The --interdiff argument allows for passing an alternative path for which interdiff executable is used. This will likely be used by the calling github action to use a custom built interdiff until mainline interdiff can do the fuzzy matching we like.

An example of how this could be integrated into our existing upstream_commit_check github action workflow is available here:
ctrliq/kernel-src-tree@f8718c0

An example of its output as a github comment is available here:
ctrliq/kernel-src-tree#621 (comment)

This was written by claude BTW. Claude used check_kernel_commits as inspiration so the calling convention and code would be similar. Hopefully similar code could be pulled out into a library and shared some day.

[PlaidCat]

I have some nitpicks, but they're the same hole I fell into using Claude as well.

[PlaidCat]

This will be interesting to see if this works with remote fork PRs

[PlaidCat]

Non-Blocking

[kerneltoast]

The final version of the fuzzy feature that I submitted as a PR upstream (twaugh/patchutils#147) requires passing --fuzzy to interdiff to trigger the fuzzy diffing, FYI.

[bmastbergen]

The final version of the fuzzy feature that I submitted as a PR upstream (twaugh/patchutils#147) requires passing --fuzzy to interdiff to trigger the fuzzy diffing, FYI.

Cool. Added --fuzzy to interdiff call

[PlaidCat]

I'm good with this first pass and getting a 80%+ code in place