Get mimetype from file extension, rather than from file content

[EpicPlayerA10]

File explorers does not infer file type from its content, but rather from its file extension. This PR makes filesystem more consistent with the files explorers.

This also fixes some bugs where sometimes you couldn't unarchive some archives.

[RMartinOscar]

Add error handling

Forget what i said

[EpicPlayerA10]

Add error handling

But the method TypeByExtension does not return an error. When a mimetype for extension does not exists, then it will just return an empty string. Thats why i do the if check later to compare if the mimetype is not an empty string.

[EpicPlayerA10]

For now this might be bad idea, because default linux mime.types file does not implement some file extensions, like .properties, and we can't edit those files in panel. So for now I will convert it to draft.

[danny6167]

This also fixes some bugs where sometimes you couldn't unarchive some archives.

Is there an open issue for this ? If not, could you open one, ideally with an example file attached.