Fix loading playlists encoded with CRLF

Reason for the change

CRLF files end with \r\n. We were not accounting for the extra \r, so were looking for music files like "myfile.flac\r"

Test plan

1. Create a sample playlist file
2. Convert to crlf with unix2dos -n input.m3u output.m3u
3. Confirm crlf endings with cat -A output.m3u (lines should end with ^M$)
4. Import playlist into Elisa

Before: error. Now: works fine

Also added a unit test.

Bugs fixed

BUG: 470721