avoid scanning a file again if it has not been modified
Summary:
avoid scanning a file again if it has not been modified
ensure we get correct behavior on application start with existing tracks
clean up of obsolete way to track removed tracks between application starts
do not yet remove tracks that have been removed when the application was not
running. This is a regression that I will fix later.
BUG: 391892
Test Plan: mostly works but subsequent starts are much faster
Reviewers: Elisa, astippich
Reviewed By: Elisa, astippich
Subscribers: astippich, januz
Maniphest Tasks: T7603
Differential Revision: https://phabricator.kde.org/D12703