copyCertificate should preserve file metadata

[ZTang813]

Cert Manager currently creates a new file with the same content during Certificate::copyCertificate function but doesn’t preserve the file metadata(rid,uid,gid,rwx etc.) from the original file. It's a nice to have feature if both content and file metadata are preserved during the copy.

[mdmillerii]

Not sure what rid referrs to. real id? I wouldn't want cert manager playing setuid. I'd think uid and gid should be configured by collection. rwx should be restricted to user until relaxed.

But this sounds like a feature not a bug and should be proposed as a patch.