Improving the interaction with the Rascal debugger

[rodinaarssen]

The only way to start the Rascal debugger is by typing in :set debugging true in a VS Code REPL. This issue is intended to keep track of how we intend to improve the interaction with the Rascal debugger.

The plan is to add a custom view to the "Run and Debug" view container, listing the active Rascal REPLs and some way to enable/disable debugging for each REPL.

Alternative considered:

• Adding a button next to the recycle bin and split icons in the Terminal view. It is not possible to add buttons there.