cobcd.py: Registering silent maintanance breakpoint for showing note about ACCEPT
Currently it sometimes see that "nothing happens" and the programmers often don't see/guess that the program actually expects an input - ACCEPT.
This is likely related primarily to our GDB frontend (Vim Termdebug) where we have 3 Windows: GDB, Terminal, code; but I think useful in general.
The effect is: GDB prompt (and Vim source window) shows the ACCEPT line without any "breakpoint xyz" note and continues so the ACCEPT is actually done as it was before - but now has the necessary visibility.