forward the join/part messages to the actor

this allows the resource actor to maintain a list of connected users.
It is assured by the dispatcher that a join message is sent only if the
user was not already using this resource. In the same spirit, the part
message is only sent to the actor if the user joined this resource
before and never left
use ResourceDispatcher for compilation actors

an actor is created per paper identifier and is maintained by \BlueLaTeX
over join/part of users
fix dependencies between modules

the compilation bundle exposes a rest interface, and thus needs the http
feature. However the core http feature does not depende on compilation
(a \BlueLaTeX server may exist without any compilation feature) nor on
the concrete synchronization server implementation.
rename Api extension trait

the bundles may provide a RestApi, not a RestApplication
move extractor to the Rest API

these extractors for int/long/date and extension are used to dispatch
the requests in Rest applications, there is no real need to make them
available to the entire blue package