Manually add duration to album tracks

[elamperti]

Is your feature request related to a problem? Please describe
Sometimes albums come with a duration of 0, which skews the album duration and scrobbling times.

Describe the solution you'd like
There should be a way to set the duration of each track in an album and in the song scrobbler.

Describe alternatives you've considered
Open Scrobbler uses 3 minutes internally when there's no duration reference, but it may not be an accurate value for some tracks/albums. Scrobbling each song one by one and adjusting the time would be tedious.

Additional context
Suggested by wolvinov on Discord

[ENDrain]

One way of implementing this could be displaying a text input field for songs with zero duration, in place where normally track duration is displayed for tracks with known duration.

Question is, how to make the purpose of the field obvious? Maybe by adding header to the track list table.

Should I try and work on this?

This seems to be related with #95 BTW