Make a command for change the aquatic movement in mobs

Mobs are not affected by the effect dolphin grace, and there is not an attribute or a tag for making them faster or slower in the water.

Implementing /attribute @e[limit=1] minecraft:aquatic_movement_speed that works in the same way that the minecraft:movement_speed attribute but in the water or just making dolphin grace compatible wiht mobs would improve some commands, maybe it will not affect a lot normal minecraft. However for people who like commands this may be so good.