Allow command renaming

[dgrothaus-ku]

It would be nice if the exporter supported renamed dangerous commands.

Some cloud Redis installations (AWS) or password protected instances use renamed CONFIG, FLUSHDB and FLUSHALL commands.

A flag to provide the name of renamed commands would make otherwise unavailable config values available.

[oliver006]

Agreed, that'd be useful to have (and this has come up before as a request).
I personally don't have a need for renaming commands but would be happy to review and merge a PR.

[oliver006]

You can now rename the CONFIG command using the --config-command flag, closing this.