always show all locations
currently the list of manual selectable gateways is filtered by supported transport.
this might be confusing, since the bridges switch is not in the same gateway-selection fragment but in the navigation drawer. the dependency between bridges switch and gateway-selection isn't obvious.
my proposal is to always show the list of all available locations. for each location entry there might be the bridges icon shown if at least one server supports obfs4 in that location. if bridges is enabled, locations supporting bridges are shown on top of the list, the other locations are shown greyed out (disabled) and below. the subtitle for those entries should contain a hint that the location doesn't support the selected transport.