Transcoding OIIOTool with padding and frames

[jakubjezek001]

#1276 (comment)

Isn't this exactly what the --framepadding argument is for in oiiotool.

I understand it's optional, but since it's a simple override optional why not just use that?

See: openimageio.readthedocs.io/en/latest/oiiotool.html#frame-sequences

Pretty sure I also used that and tested that in: #1217

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#1276 (review)

Approving this PR as this code works and fixes the issue.
If that's a urgent/critical bugfix, I believe this patch is good enough.

Now as flagged, there is a specific --framepadding argument that could be used here.
Just wanted to add that from my tests, --framepadding needs to be there along --frames.

# Works
oiiotool.exe --info -v -i:infoformat=xml C:/Users/robin/output.948845-948869%07.exr

# Works
oiiotool.exe --info -v -i:infoformat=xml C:/Users/robin/output.#.exr --frames 948845-948869 --framepadding 7

# Does NOT work
oiiotool.exe --info -v -i:infoformat=xml C:/Users/robin/output.948845-948869.exr --framepadding 7

Originally posted by @rdelillo in #1276 (review)

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