Add selected state for manually added bridges

Situation you are using a bridge. config > connection 'use a bridge' is ticked on. Go to 'manual selection', see that obfs4 is selected (you were using a bridge already). > get new bridge with the Ask the bridge bot option. > I need new bridges > use bridges. Then use the back button (top left) and see that both obfs4 and snowflake are not switched on anymore, none selected.

EDIT: see #169 (comment 3042559) for the actual change request.