Adding ability to read/write Permission Configs and cli to access them

- Added the ability to set/list/remove permission configurations from prefixes.
- Most of this was a mimic of what Spencer wrote for the zone configurations.
- Also consolidated some of the repeated code where I could.

Once this is merged, I'll create a similar treatment for Accounting Configurations.
One post-hoc justification for calling them perm instead of acl is the high likelihood the struct expands to hold things other than acls. I originally toyed with some adjunct to priority here--certain users would get preferential priorities, meaning less waiting on reads, fewer aborts on writes, etc. Not sure what will go here over time, but I think "permissions" is the right concept and "acl" is too restrictive.