feat(server): Implement CONFIG HELP command

[highpon]

Related Issue: #857

The CONFIG HELP command is implemented in this PR.
The implementation of the CONFIG HELP command in Redis 7.2 was used as a reference.
The notation of the CONFIG HELP command in Redis 7.2 is as follows.

 1) CONFIG <subcommand> [<arg> [value] [opt] ...] . Subcommands are: .
 2) GET <pattern> .
 3)     Return parameters matching the glob-like <pattern> and their values.
 4) SET <directive> <value> 5) Set the configuration <directive> <value> .
 5)     Set the configuration <directive> to <value>.
 6) RESETSTAT
 7)     Reset statistics reported by the INFO command.
 8) REWRITE
 9)     Rewrite the configuration file.
10) HELP
11)    Prints this help.

The CONFIG REWRITE command is not yet implemented in the current DragonflyDB.
The newly implemented CONFIG HELP command excludes the CONFIG REWRITE command.

[romange]

Thank you! We have not reached conclusions that REWRITE is needed at all.

[chakaz]

Thanks for your contribution!
Please see super small nits, but otherwise looks good :)

[chakaz]

Suggested change

	" Prints this help."};
	" Prints this help."
	};

[chakaz]

Suggested change

	rb->SendSimpleStrArr(help_arr);
	return;
	return rb->SendSimpleStrArr(help_arr);

[highpon]

@chakaz
Thanks for your review!
PR updated.

[chakaz]

thanks again!