Create AdminIT tests (similar to ShellServerIT)

FaTE command functionality has moved to the Admin command. Previously, the functionality was tested in ShellServerIT. This should make it easier to see that Admin functionality is being tested and isolate changes to a single test as the Admin command evolves.

Create a test similar to ShellServerIT that consolidates Admin command testing. Individual tests like FateSummaryIT (PR \https://github.com/apache/accumulo/pull/2950) should be moved into the new test. There may be others that are testing pieces that should be moved too.

The new test should exercise all of the Admin command options.

Start by reading ShellServerIT and FateSummaryIT, including the changes proposed in PR #2950, to identify Admin command coverage currently spread across tests. Create an Admin-focused integration test that consolidates those checks and exercises every Admin command option; done means the existing relevant coverage is moved or represented there without gaps.

Written by the indexing model from the issue text.