performance: Many Entity Activation Range Improvements

1) Immunity no longer gives 20 tick immunity, each immunity check can
give its own tick value on how long it lasts, drastically cutting down on most to 0-1 ticks.

2) Fixed Villager Immunity to use proper 1.15 check for Breeding.

3) Fixed Water Mobs being 100% immune due to the inWater check...

4) Fixed flying mobs being 100% immune due to the !onGround check...

5) Made Insentient mobs only check for the hasTasks during immunity check window, not every single tick. this made them way more active than desired
  - this puts behavior closer to inline with my original behavior in Spigot, but still does some checks to allow them temporary immunity, just not as much as before.

6) Inactive Entities would "inch" while trying to move, effectively getting nowhere. Now while an entity is inactive, it just won't even try to move.
  - this saves us from the expensiveness of Entity movement 1 out of 20 ticks. Now they will only move while either active or triggered a true immunity.

Spigot-Server-Patches/Fix-items-vanishing-through-end-portal.patch

@@ -13,7 +13,7 @@ Quickly loading the exact world spawn chunk before searching the
 heightmap resolves the issue without having to load all spawn chunks.
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 659591e02..6e41a5506 100644
+index e10740a65c..c4e85b86d9 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements INamableTileEntity, ICommandListener, Ke