Debug: call stack commands arguments

[isidorn]

We need to do a couple of things:

1. Currently for commands which are contributed for threads we pass the threadId as a number argument. However this is not enough when you are debugging multiple sessions. Since the threadId does not uniquly identify the thread across sessions. Due to that we should send a structured object which contains the sessionId and the threadId
2. For stackFrame we pass the source uri string. Which is also not enough to identify the stackFrame. It should laso include the threadId and the sessionId
3. We need to add documention which explains what contexts we pass for contributed call stack commands

We will probably try not to break the current behavior, but add additional arugments after the current argument.

@testforstephen is Java contributing call stack commands for threads?
@roblourens @connor4312 fyi since the node debugging contribues Skip File commands
@weinand fyi