Design task: T65607
The patch adds a new flag for each animation space, allowing to hide the markers region per editor. It also changes markers' UI and operators accordantly.
- In anim_markers.c a new function substitutes ED_operator_animview_active in the operator polls that also checks if the area is drawn in the editor in which the operator is called.
- In rna_space.c a new property is set per animation space, called draw_marker_region
- The versioning part does seem to work but I'm really not sure if I did it right
- The options to show the markers region and markers lines are put in a sub-menu of the View menu In action and shapekey mode of the Dopesheet editor, Show Pose Markers is also put in this menu and renamed to Toggle Pose Markers.
- If the markers region is not active then the Marker menu gets hidden
- Driver editor: removed marker menu and don't allow to use marker operators.