Explicitly set thread ID when getting stack depth

Found by @jonahgraham during code review:

We have a couple of calls to `mi.sendStackInfoDepth` which do not receive a threadId parameter although we have the knowledge in the surrounding code.

This should in theory be fine because the affected functionality is always executed on the currently selected thread. Which should be correctly selected in GDB. But we should make use of exact knowledge when we have it, like for most of these calls. Especially if there is a lot going on in the GUI which could change the thread selection while operations are in flight.