Mimetype detection for hidden files

[mwalbeck]

Implement mimetype detection for hidden files, so hidden images and text files gets recognized as such, and not as generic files. This would also ensure that if you upload a hidden file to Nextcloud, and then rename it to a none hidden file, you don't have to update the filecache for it to have the correct mimetype.

This is something I would be willing to look into myself.

Any thoughts?

[nickvergessen]

Sounds good, and feel free to look into it.

[rullzer]

Fixed by #3212