Check MIME types before decompressing to warn mismatching formats

[marcospb19]

When decompressing, we usually rely on the file extensions being correct ("usually" because #134 will be added).

We should warn the users when the MIME type of some time does not match the decompression method we are using, giving an `[Y/n] dialog to ask if they want to proceed or skip.

Because of implementation limitations and complexity, we should check the MIME only at the surface of the file, even tho ouch supports files like archive.tar.gz.xz.bz2.zst.lz, our warnings should not decompress all the steps for checking MIME, only what can be read directly.

Implementation details: implementation should save the bytes in a small Vec/array instead of reading from the same file twice, because we also plan on support reading from STDIN, and you cannot read from it twice.

(Previously #5.)