support for "date added" and "favourite" fields

[sterling-tenn]

let me know if there's anything weird with this, but this solves my issue #5 pretty well

there may be a couple edge cases that I might look into at another time but for the most part I'm satisfied with this

[Stampede]

It looks mostly OK but I don't have a way to test it. Something I noticed missing is that when something is "loved", then that action gets a timestamp, but you leave it without a timestamp:

annotation_entries.append((generate_annotation_id(), userID, item_id, entry_type, play_count, play_date, rating, loved, None)) (the None at the end sohuld have a timestamp if it's actually loved).

It may not matter, or maybe that is used in Navidrome somewhere non-obvious like for smart playlists, or for ND to make suggestions for favorite songs or something.

If a song is unloved, then leaving that as None is how ND does it already.

Thanks for the PR! Because I can't really test it, I think I will make another branch and then merge your changes into that and people can use it if they want and report issues. But I am not too good at the github thing so gimme a day or 2 to figure out how to do that.

[sterling-tenn]

Yeah, I didn't put any timestamps for the loved field since that's perfectly fine for how I used it in iTunes. I didn't really care about the timestamp for that, it was just a little indicator for me.

I also just realized that in the case where a song doesn't have a "last played" date (ie never been played before) something fails when updating the "date added" field. I may look into that if I have a time, but it's pretty much a non-issue for me.

One more thing I might change later is just a quick option to specify what path the it_root_music_path points to, because of this #4 (comment), but that's a trivial thing

[bitte-ein-bit]

I can confirm loved is working for me. Date added not. I had to change it according to the above review.

[bitte-ein-bit]

Suggested change

	if dateadded > d1[id]['date added']: d1[id].update({'date added': dateadded})
	if dateadded > datetime.datetime.fromordinal(1) and dateadded < d1[id]['date added']: d1[id].update({'date added': dateadded})

I think you want to use the earliest date that is defined. All my files had the date I initially imported the files from the disc.