Fix PFDEBUG commands flag (#8222)
Fix PFDEBUG commands flag (#8222)

- Mark it as a @hyperloglog command (ACL)
- Should not be allowed in OOM
- Add firstkey, lastkey, step
- Add comment that explains the 'write' flag
JackieXie168/redis,JackieXie168/redis,JackieXie168/redis,JackieXie168/redis