Make the elasticsearch dependency part of the sdk

Elasticsearch is at the center of the Nexus ecosystem so having it as a simple plugin does not make sense.

The view part can remain a plugin for now but the client (and the sink) should move to another module so that we can break those dependencies between plugins that are not necessary.

The tests around Elasticsearch are also the ones taking time so isolating this module a maximum would help not to trigger them as much as we do now and gain time running the tests.

The same thing with the dependencies between plugins, we could imagine in the long run not to run the tests for the archive plugin because there has been a change on the elasticsearch one.