Add Support for ACL GETUSER Command

[kevinmichaelbowersox]

Feature request type

sample request

Is your feature request related to a problem? Please describe

Currently Garnet Cache does not support the ACLGETUSER command. This command is used to obtain the ACL rules for a specified user. This command is useful for inspecting individual identities authorized to access the cluster.

Describe the solution you'd like

I would like to be able to issue a command against Garnet in the form of ACL GETUSER {USERNAME}. The command would return details about the specified users ACL in a RESP protocol compliant array with this output:

1) "flags"
2) 1) "on"
3) "passwords"
4) 1) "#**REDACTED**"
5) "commands"
6) "+get +incr"

In the case where the user does not exist the command should return null.

Describe alternatives you've considered

Currently the ACL LIST command is supported. A client interested in this information could parse the response of the list command for similar information about a user's ACL. However, with ACL GETUSER this parsing is not required.

Additional context

I have a forthcoming contribution/PR that implements this command for the team's consideration for inclusion into the project.