IDEA-126221 Threads view is not navigatable
uninstaller: association fixed.
[git] IDEA-90059 Notify "changes shelved but not restored" only if there truly was something stored
[git] remove unused test class
[git] IDEA-81935 Refresh file if not found, log if still not found
[git] remove unused method
Merge remote-tracking branch 'origin/master'
[git] IDEA-81935 If no changes were found to show, just show paths

* Extract the FilePathChangesTreeList to a separate class for reuse.
* Pass paths reported by Git along with the possibly empty changes.
* If for some reason there are no changes to show, show the simplified
  dialog version with file paths and no changes operations available.
[git] extract method to GitUtil for further reuse
extract class for further reuse
[git] move method to GitUtil for further reuse
[git] IDEA-90058 Fix empty Untracked files would be overwritten dialog

Behave the same way as in the "local changes would be overwritten" case:
show the simple paths viewer (IDEA-81935):
* Pass root + relative paths to the UntrackedFilesNotifier,
  and convert to VirtualFiles there.
* Do the same for the dialog with rollback proposal in
  GitBranchUiHandlerImpl.
DialogBuilder: let specify the north panel
[git] Extract class for further reuse
[git] IDEA-87853 Detect 'local changes' error on pull and display them
EA-57760 Fix already disposed
[git] IDEA-101216 Focus to the branch list by default
[git] cleanup: remove trivial javadocs
[git] IDEA-81935 Detect "local changes" error on merge: reuse fix for pull

GitPull and GitMerge actions are actually almost the same.
Dialogs are different, and GitHandlers (command + parameters) are
different, but the rest can be reused.

* Collect the needed information from the dialog to some structure:
  the DialogState. This is made for both actions separately.
* Execute the action in the background thread, detect the "local
  changes" error, show the result - this is copied from GitPull
  (a better implementation from the two).
[git] Detect "untracked files" error on pull and merge

Relates to IDEA-81935.