Adding ACL support for modules (#9309)

This commit introduced a new flag to the RM_Call:
'C' - Check if the command can be executed according to the ACLs associated with it.

Also, three new API's added to check if a command, key, or channel can be executed or accessed
by a user, according to the ACLs associated with it.
- RM_ACLCheckCommandPerm
- RM_ACLCheckKeyPerm
- RM_ACLCheckChannelPerm

The user for these API's is a RedisModuleUser object, that for a Module user returned by the RM_CreateModuleUser API, or for a general ACL user can be retrieved by these two new API's:
- RM_GetCurrentUserName - Retrieve the user name of the client connection behind the current context.
- RM_GetModuleUserFromUserName - Get a RedisModuleUser from a user name

As a result of getting a RedisModuleUser from name, it can now also access the general ACL users (not just ones created by the module).
This mean the already existing API RM_SetModuleUserACL(), can be used to change the ACL rules for such users.

src/multi.c

@@ -228,7 +228,7 @@ void execCommand(client *c) {
                 reason = "no permission";
                 break;
             }
-            addACLLogEntry(c,acl_retval,acl_errpos,NULL);
+            addACLLogEntry(c,acl_retval,ACL_LOG_CTX_MULTI,acl_errpos,NULL,NULL);
             addReplyErrorFormat(c,
                 "-NOPERM ACLs rules changed between the moment the "
                 "transaction was accumulated and the EXEC call. "