Implementation of Invariant Subsystem Mode Status Requesting

[chgio]

As shown in 3cb6756 on bug/szy-enforce-false-assumptions-mode-change, trying to implement #13 exclusively through enforcement only moves the assumption to before the initialisation sequence, but doesn't get rid of it.
As cleverly suggested by @ZonaDashti, this could be achieved by simply requesting a *-Mode-Status-Report-T from a subsystem without commanding a change to a *-Mode-T first.

Off the top of my head, this would require adding a new request * mode status interface from the OBC's system_mode_manager to each subsystem's *_mode_tracker to just request the current mode status, which could be simply delivered through the existing report * mode status interface.
Internally, the system_mode_manager should be fine just going into the Wait_* state after the request, but some extra logic should be added at the "output stage" because we probably wouldn't want to try downlinking a whole report every time.

These requests would be triggered at the beginning of the initialisation procedure as elicited by #13; additional interesting possibilities could also be upon request from the ground station, and cyclically to generate and store telemetry data.
#15 follows up about the first addition.

[chgio]

I'm thankful to past me for only filling in the *-Mode-Status-Report-T SEQUENCE with the current *-mode and *-last-op, and no target-*-mode as with the Mission-Mode-Change-Report-T. I admit I didn't do it with this in mind, but it's turning out convenient :)