Add some Canon RF lenses w/ ext (backport #3116)

[mergify]

Edit: Second commit is purely cosmetic, more consistent w/ Canon's own Exif.Photo.LensModel / Exif.Canon.LensModel strings...

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This is an automatic backport of pull request #3116 done by Mergify.

[mergify]

Cherry-pick of 0643639 has failed:

On branch mergify/bp/0.28.x/pr-3116
Your branch is up to date with 'origin/0.28.x'.

You are currently cherry-picking commit 06436390.
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  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   src/canonmn_int.cpp

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally