Add duration file for tracks
Add duration file for tracks

Also add yet another macro to avoid boilerplate.

Signed-off-by: Anton Lofgren <64e2cb85477d4abaea4b354af986fde12a3e64f3@op5.com>

raoulh/spotifile,chelmertz/spotifile,catharsis/spotifile,raoulh/spotifile,catharsis/spotifile,chelmertz/spotifile,chelmertz/spotifile,catharsis/spotifile,raoulh/spotifile