Finding invalid extensions

[qarmin]

Support for finding files with invalid extensions

Algorithm

• Get original extension of file
• Check what content is inside file(returns single extension)
• To provided extension, mime type is provided
• All extensions from this mime type are loaded
• App check if original extension is inside provided ones by mime type

Due to not 100% perfect extension finding by used libraries, there are provided several workarounds to lower amount of not correctly detected records.

App sometimes can show invalid results especially with system files or less known extensions, so I suggest to use it only for well known own files like e.g. photo collections.

TODO
Button to rename files(not sure how it should work, because most of files have multiple possible proper extensions)

Fixes #611
Related to #651

[qarmin]

HELP IN FINDING PROPER LIBRARY NEEDED

Well,
Entire logic is inside, but I didn't read properly description of mime_guess crate - "MIME/MediaType guessing by file extension." XD (it was quite strange that ~500000 checked files had proper extensions)

So, I'm looking for replacement that library.
Currently looks that this library can be proper:

• https://crates.io/crates/content_inspector
• https://crates.io/crates/xdg-mime