FR: use Debugger console for GDB comands (or at least allow them there)

currently everything in the debugger console seems to be handled as an expression to evaluate - but that's already possible using the watch pane in the debugger; other extensions therefore allow you to execute real GDB _commands_ (so you can still "print" but also load python debug extensions, asking for inferior details, ...)

Please make a breaking change (with likely not too much people being effecting, telling them they can use the watch pane) to keep the debug console to allow the developer to directly operate with the debugger (that's what it is for).
If you feel this isn't possible then add something like "if the first word is 'gdb' (or '-exec') then we send anything afterwards top gdb)