Add boolean suppression DebugSessionOptions

[sgraband]

What it does

Add options to suppress the debugging statusbar, toolbar and view.
As well as the saving before starting a debugging session.

Fixes #12015

Contributed on behalf of STMicroelectronics

Note:
Parent/child sessions are currently handled as followed:

• For the saving supression only the root session is taken into account as this could have unintended side effects (saving files when not wanted), if a child session specifies something else than the parent session.
• For the other three supressions (debug view, toolbar and statusbar) the value of the current session is evaluated. If there is no value the nearest parent session will be evaluated.

I mostly went with two different approaches here due to the significance of the actions (saving vs graphical-only), but your input is welcome and i will gladly unify the approaches, when the "better" solution is identified.

How to test

• Install this extension: helloworld-sample-0.0.1.zip
  It registers a few commands that start the "Launch Browser Backend" debug config with different options set.
• Open theia and the theia repository as the workspace.
• Add the following to your setting.json file:

"debug.saveBeforeStart": "allEditorsInActiveGroup",
"debug.openDebug": "openOnSessionStart",
"files.autoSave": "off",

• Trigger one of the Start Debugging commands. It says in parenthesis which options are enabled.
• See if the behavior is correct:

suppressDebugStatusbar?: boolean
When true, the window statusbar color will not be changed for this session.

suppressDebugToolbar?: boolean
When true, the debug toolbar will not be shown for this session.

suppressDebugView?: boolean
When true, the debug viewlet will not be automatically revealed for this session.

suppressSaveBeforeStart?: boolean
When true, a save will not be triggered for open editors when starting a debug session, regardless of the value of the debug.saveBeforeStart setting.

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[tsmaeder]

A couple of questions/suggestions

[tsmaeder]

There does not seem to be an option in the settings UI for debug.saveBeforeStart. Is this maybe missing in the preference schema?

[tsmaeder]

I'm fine with the changes, but we need to decide whether the support for the saveOnStart preference should be in this PR or not. If not, could you please open an issue so we can track the problem?

[sgraband]

I created #12319 for the follow up.

[tsmaeder]

Looks good to me now.