Allow Piercing Enchant (currently exclusive to crossbows) on Tridents.

It would do exactly what you would expect. When a Trident with piercing is thrown, it'll act just like an arrow shot from a piercing crossbow, allowing us to hit multiple enemies in a line. Loyal Tridents would then return after hitting a block or falling into the void, as normal.

Since the Trident is a weapon with durability, each enemy hit would count towards durability lost.