[master] Fix issue 63779: Handle xattr.read unicode errors by mimicking builtin xattr

[sheagcraig]

What does this PR do?

Apple puts bytes which are not decode-able into some common xattrs. This can be verified by downloading just about any app (from the web or the app store) and using the builtin /usr/bin/xattr /path/to/app on it and then attempting the same thing with Salt (salt-call xattr.list /path/to/app).

If you look at the actual bytes, it's tempting in some cases to try to parse them; often they are binary plists. However, these fail to parse with the builtin python plistlib (which does handle binary plists now). I tried it, they don't parse with NSPropertyListSerialization either, and even if they did, Salt for Mac no longer includes PyObjC so I'm not sure that would be helpful.

Regardless, I've seen other xattrs in the wild which are not binary plist and also fail when trying to decode to Unicode.

What issues does this PR fix or reference?

Fixes: #63779

Previous Behavior

Raises CommandExecutionError

New Behavior

Uses the bytes.decode argument errors="replace" to sub in � for anything that fails decoding. (This is what the builtin xattr tool does on output as well).

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

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[sheagcraig]

I'm working on the test. The existing integration test I imagine won't work since I can't write bytes using the function, so I have to start a unit test from scratch.

[sheagcraig]

Okay-test is in and this should be good to go. Also cut #64041 to the 3006.x branch.

[sheagcraig]

@garethgreenaway anything I need to do to get this merged as well? Thanks!