Guess the file content's MIME type using File::MimeInfo::Magic then if type can be guessed and file doesn't yet have extension or has unmatching extension then add an extension

Changes for 0.607 - 2023-06-30

• First release, split from App-perlmv.
• Use File::MimeInfo::Magic instead of LWP::MediaTypes because the latter only use filename instead of content.