Consolidate ThriftClient code to use ServiceDescriptors

**Is your feature request related to a problem? Please describe.**
The thrift client connection code uses various different methods to get connections to servers.
These various classes make troubleshooting needlessly complicated and could be simplified.

**Describe the solution you'd like**
The thrift client code should be consolidated to a single ThriftClient class which uses ServiceDescriptors to return the desired thrift connection type.

This simplified code should also implement the debug option from TServerClient
`org.apache.accumulo.client.rpc.debug.host` that allows the client to select the specific host for debugging purposes.