De-couple cache view installation and state transfer (consistent hash installation)s

We need to know the primary owner of a key in order to do pretty much anything, and every member of a cache view should compute the same primary owner at all times. So we need a 2PC cache view installation immediately after any leave to ensure that every node determines the primary owner in the same way - we can't coalesce leaves.

However, it's highly desirable to coalesce state transfers caused by a node leaving - perhaps because we are shutting down half of the cluster to do an upgrade. So we should separate the state transfer from the cache view installation, and each one should have its own 2PC process.