Decompose admin command into separate commands

[dlmarion]

Closes #6086

[dlmarion]

There are two tests in CheckServerIT that are not passing

[keith-turner]

Ran this locally to see what it looked like. This is great, could really improve and organize what is currently there. Was wondering about the following groupings of commands, not suggesting that for this PR just posting thoughts about eventual direction. Not sure if this would be good to do in this PR or not.

file group # wal,rfile
  create empty rfile
  rfile info
  gen splits
  split large
  wal info

volume group #
  list-volumes
  add volume ?
  
start group # start server processes
  start compactor
  start manager
   etc

server group  # management of running servers
 ping
 service status
 stop-all
 stop-managers
 stop-servers
 list-compactors
 zoo-zap

fate group # management of fate operations
 list
 fail
 kill

compaction group #these may be duplicated in the shell, not sure
 cancel 
 list

admin group  # whatever is not in another group above (dropping the current other group and letting admin be the catchall)

Also, there is probably a lot of room for improvements in follow on issues to get more consistency across commands.

Also wondering about the core, if there is a way to have those commands at the top level

[dlmarion]

@keith-turner - no issues here with renaming and regrouping things, but I'd rather do it in follow-on PRs, just so that this doesn't continue to grow.

[ctubbsii]

I'm not sure "admin" is the best catch-all because users can just throw new commands on the classpath. But, overall, I think this is headed in a good direction.

[ctubbsii]

I'm not a fan of mixed case in package names. How about this instead?

Suggested change

	package org.apache.accumulo.server.util.adminCommand;
	package org.apache.accumulo.server.util.admin.cli;

[dlmarion]

I was just following the established convention. ...util.checkCommand, ...util.fateCommand, and ...util.serviceStatus already exist. If we want to change the package names, I think we should do them all together in a different PR.