Filter by text file

Allow smart playlists to be created from songs in a text file with a configurable format.

It should support wildcard matching with *, in which case all matches will be added.

Something like this:
```yaml
rules:
  and:
    type: file
    file: playlist_1.txt
    format: [artist, title]
```

And a file as follows:
```
Artist A - Track A
Artist B - Track *
```