Timeline clips on tracks that are locked are still selectable using the keyboard arrow keys or tab from a track selection.
Clips on locked tracks should not be selectable.

repro:
- open attached project
- open clipSelect scene
- open Timeline
- select Cube GO
bug1...
- select a clip and use the keyboard arrow keys to move the current selection to clips that are locked. Expecting clips to be ignored, stay un-selected, and the next available clip is selected.
(see attached gif)
bug2...
- select a locked track and use "Tab" on the keyboard to select the first clip on the track... clip should not get selected.

both these bugs have the side effect of the user not being able do an edit operation (ex: move clip) because a clip on a locked track is also selected (often by accident).