Add new property in the record.

The channle_id is needed to represent the channel to be played on the
time of the program specified as start and end time.
Tweak the epg buttons
Fixes for the linter
Use external data provider for channels.

This change is preparation for allowing the epg component to handle epg
queue as reference to an object. That object should be able to access
the channel data fully (including search in folders) in order to be able
to play back the schedules made from EPG.
Remove outline from epg list item.