.Interpreterfailexceptionisnotpropagatedtofrontend

What is this PR for?

This PR would address the issue of Interpreter fail exception is not propagated to frontend. This is due to the bug fix of restarting button issue. Make referenceCount as number of sessions attached to this process. Open and close all the interpreters in one session together. I don't think there's scenario for close a single interpreter for now.

What type of PR is it?

[Bug Fix | Improvement]

Todos

• [ ] - Task

What is the Jira issue?

• https://issues.apache.org/jira/browse/ZEPPELIN-2294

How should this be tested?

I don't have time to write test, just verify zombie process issue manually in the following scenario
* Per User + Isolated
* Per Note + Isolated
* Per User + Scoped
* Per Note + Scoped

Screenshots (if appropriate)

Before