HTTP Lane Directives

[c9r]

Extract the HTTP lane routing logic from swim.service.web.WebServer into a generalized swim.service.web.HttpLaneRoute class.

• Implement HttpLaneRoute, taking an EdgeContext, a node URI, and a lane URI as parameters.
• Add a LaneAddress POJO to swim.runtime, with hostUri, nodeUri, and laneUri fields (i.e. a 3-tuple of (Uri, Uri, Uri)).
• Implement HttpLaneDirective, taking a java.util.Function<WebRequest, LaneAddress> as its parameter, which behaves like HttpLaneRoute, but dynamically computes the address of the HTTP lane to which it routes.
• Modify swim.service.web.WebServer to use HttpLaneRoute, keeping it compatible with the current fixed-function configuration format. That format will be deprecated once the Web routing DSL (Web Routing DSL #6) is ready to replace it.

Due to the lack of extension methods in Java, we unfortunately can't add a WebRoute combinator function for producing HTTP Lane routes.