Resource Group Configuration follow-on tasks

Here is a list of follow-on tasks/issues from the comments in #5749

- [x] Specifying `-rg` in config command without `-s` or `-d` should fail or warn - #5862
- [x] Create `createresourcegroup` command instead of `resourcegroup -c` - #5860
- [x] Create `deleteresourcegroup` command instead of `resourcegroup -d` - #5860
- [x] Add ability to specify file with properties when creating resource group - #5860
- [x] Add test to ResourceGroupConfigIT that tests permission checks
i.e. a user without SYSTEM permission can't create/delete resource group -- #5864
- [x] Check for ResourceGroupPropUtil duplicating code from Property.java - addressed in [1eefb82](https://github.com/apache/accumulo/pull/5749/commits/1eefb8272554e60e70000bbb5404695793803f71)
- [x] Allow ResourceGroupConfiguration to set some fixed properties (or remove altogether) - #5865
- [ ] Look at allowing some RPC props to be set at resource group level - see comment below
- [x] ConfigCommand does not display rg overrides if prop not defined at system - see comment below, I think this is OBE
- [x] Would be nice to have an IT w/ three RG w/ three different sets of props where some overlap and some do not. Then request props for each RG via API and ensure only system+RG requested are seen. - #5864
- [x] Seems to be able to set fixed props (was just experimenting in the shell), but maybe can not see them? When setting the fixed prop for a RG in the shell do not see warning. Should see a warning similar to when setting a fixed prop at the system level. - #5865