terminal: Add right-click in terminal to create a new selection if none is present (#29131)
Ho Chun Lau
created
This PR adds functionality to right click in terminal create new
selection if none present. The selection is identical with double click
a text in terminal, plus the logic is moved from the double-click in the
terminal::mouse_down.
Closes #28237
Release Notes:
- Adds functionality to right click in terminal create new selection if
none present