FLUID-5542: Queued DataSource

Added a Queued DataSource that can combined with different requestQueues to synchronize, throttle, and debounce requests to a DataSource.

http://issues.fluidproject.org/browse/FLUID-5542

This is an extension of the work started in https://github.com/fluid-project/metadata/pull/43
I guess i understand generally what you mean here, which is to use fluid.promise.sequence to replace the test drives and the fluid.tests.queuedDataSource.assertDelayedRequests method. However, I'm not following your instructions on how to actually do this.