Create seperate solutions in couchbase-net-solution to reduce the working size

The purpose of this ticket is to create "sub" solutions to reduce the working size of the solution when someone is working on a specific project. For example, there may be a couchbase-net-client-onpremise which only includes sub-projects related to on-premise. Another example is a solution called couchbase-net-client-stellar which only includes sub projects related to Protostellar. This should increase build times and reduce complexity as the solution will be much smaller and more concise. The original couchbase-net-client.sln solution will still remain and be the default solution when the repo is checked out.