Fix debugger behavior with multi-session debugging

[SaracenOne]

This fixes several bugs in the in-editor debugger associated with the ability to launch multiple instances of a game for the purpose of testing multiplayer logic locally.

• It fixes the script editors debug menu containing step, break, and continue, which do not work if launched from an instance session other than session 1. It also correctly contextually greys out options depending on whether the session has hit a break point or not.
• Adds proper callbacks to all breakpoints to be removed when toggle from the breakpoints menu in a session tab other than 1.
• Stops the execution indicator from appearing when switching tabs to a session which has not hit a breakpoint.

This has not been tested with external debuggers, but at the very least, I don't expect it cause regressions, but would recommend a review from someone actively making use of an external debugger.

Closes #82867

[SaracenOne]

Putting this back under draft for the time being. There's still some issues.

[SaracenOne]

Okay, reopening this since I think I've resolved the issue now.

[Faless]

Amazing work 🏆 !

I've tested it a bit with a couple a project, seems to work seamlessly.

[akien-mga]

Thanks!