fix: Removes scale speed by dex for monsters, fixes NPC movement/thinking speed (#1019)

* Removes scaled speed by dex for monsters
* Changes scaled speed by dex for pets (HS+ expansion) to be 400ms -> 100ms between 50 -> 200 dex
* Removes speed changes that were broken for various mobs
* Combines "Legacy" speed and renames the class to `NPCSpeeds`
* Creates speed "classes" (slow, medium, fast, very fast)
* Introduces a new overridable property `SpeedClass`. Register a new speed class using `NPCSpeeds.Register()` and then set the speed class to bulk/mass apply speeds.

Order of speed determination:
1. SpeedMod
2. SpeedClass property (not null)
3. SpeedClass entry in Data\npc-speeds.json for that type
4. "Fast" (200ms Active, 400ms Passive)

Projects/UOContent/Items/Talismans/TalismanSummons.cs

@@ -11,7 +11,6 @@ namespace Server.Mobiles
 
         public BaseTalismanSummon() : base(AIType.AI_Melee, FightMode.None)
         {
-            SetSpeed(0.3, 1.0);
             // TODO: Stats/skills
         }