Prior to this change, the server test was repeatedly performing io on
the portfile while the server was starting up. This adds a modest sleep
so that the test is just as responsive without doing needless io.
Initial draft for bsp support.
This shows two communication pattern around BSP.
First, if the request can be handled with the build knowledge is readily available in `NetworkChannel` we can reply immediately. `BuildServerImpl#onBspBuildTargets` is an example for that.
Second, if the request requires `State`, then we can forward the parameter into a custom command, and reply back from a command. `BuildServerProtocol.bspBuildTargetSources` is an example of that since it needs to invoke tasks to generate sources.
Ethan Atkins
Eugene Yokota
Adrien Piquerez