Support spatial (multi) selection on MaEditor name list.

MSA editor should support multi-regions selection.

Details:
1. Multi-selection should have unified X-range: all regions should have the same x & width.
2. Regions should not overlap.
3. Multi-selection can only be set in the name list when Click + Control is used.

This task is to support geometry manipulation in the name list.
Special tune-up for sequence view, copy-paste and other actions based on the selection state will be done next in as part of separate issues within the same epic.