Allow REPL without breakpoint

[theraot]

Implements godotengine/godot-proposals#11891

Implementation notes:

• I check if the stack frame is greater or equal to zero, because in the context of no breakpoint it is -1
• The check for the returned instance is already there, so I kept it
• The code from taking the globals is based on "get_stack_frame_vars" a bit above (btw, members also requires an stack frame so they are out of the question)
• I also don't know if there is a way to access static classes, with the implementation as it is at the time of writing they are not available.

I'm cofounder of Psyches Media, so I'm going to say Psyches Media sponsors this.