Improvement: Show active command line options / parameters values in GUI

[fanquake]

I think it would be very professional and inspiring confidence, if the user could verify the settings from the command line/the config file(bitcoin.conf), in the running instance in the GUI.

Maybe in the GUI window "help"->"command line options" for every option that sets a parameter, there could be a line inserted, that shows the current active value of this parameter.

E.g. if one has set
onlynet=tor
in bitcoin.conf
it would be nice IMHO, if the user could verify that this setting is active, in some window.

Maybe even with a reason (e.g. state "listen=0 because proxy parameter is set")

Moved from bitcoin/bitcoin#8165.