Add reflection for crystals (#16426)

Content.Shared/Projectiles/ProjectileCollideEvent.cs

@@ -0,0 +1,7 @@
+namespace Content.Shared.Projectiles;
+
+/// <summary>
+/// Raised directed on what a projectile collides with. Can have its deletion cancelled.
+/// </summary>
+[ByRefEvent]
+public record struct ProjectileCollideEvent(EntityUid OtherEntity, bool Cancelled);