PlayRouteSupport

Shared by Analyzer::Java::Play and Analyzer::Scala::Play: both read the same conf/routes grammar, so the route-line helpers (path params, action-signature params, include collection) are one copy here.

It is a mixin because the two analyzers have no common base below Analyzer. The includer supplies read_file_content, resolve_included_routes_file and request_route_param_type? — those differ per language (Scala knows RequestHeader/MessagesRequest and resolves duplicate routes basenames by directory).