ReentrantLock.getOwner() to help clean up scan sessions

[DomGarguilo]

Closes #3579

This PR replaces the semaphore with a ReentrantLock in Scanner. A new private class, InterruptibleLock was created to expose the protected getOwner() method.

I am not too sure how to test these changes so have not added any tests yet. Ideas/suggestions are welcome.

[dlmarion]

LGTM, I kicked off full IT build for this PR.

[EdColeman]

@keith-turner - would running your new scan consistency test for an extended period also stress these lock changes?

[dlmarion]

Full IT build passed successfully

[keith-turner]

@keith-turner - would running your new scan consistency test for an extended period also stress these lock changes?

The test will definitely stress the read method modified in this PR. However I do not think it will stress the close method.

I think to stress this the test would need to do the following

1. Start a scan over range x to +inf
2. Do not read all data, leaving a scan session on the tserver to be cleaned up

I don't think the test does this, but it should if it does not. Some of its scans should randomly be open ended and not read all the data. On a long running test this would trigger the session clean up that calls close on an idle session.

[keith-turner]

@EdColeman I created #3656 to add an open ended scan to the test. However I am not sure if will leave a scan session open on the tserver. A scan may have to not read all data from a scanner and not close the scanner to leave a scan session open. I am not sure though. Wonder if the test should randomly not close scanners also.