Add 1.9+ PvP 'Cooldown' (#768)

* Add 1.9+ PvP 'Cooldown'

This commit adds a subtitle that acts as the Java cooldown. This is an optional feature disabled in the config with `show-cooldown`. This does not appear on plugins that use OldCombatMechanics.

* No need to bump up the config version; I was just tested with OldCombatMechanics

* Use simpler casting

* Use session variable of lastHitTime for theoretically better performance

* Reuse attribute value calculation from AttributeUtils

* Remove unused imports

* Revert config version update in config.yml

bootstrap/sponge/src/main/java/org/geysermc/platform/sponge/GeyserSpongeConfiguration.java

@@ -129,6 +129,11 @@ public class GeyserSpongeConfiguration implements GeyserConfiguration {
         return node.getNode("allow-third-party-ears").getBoolean(false);
     }
 
+    @Override
+    public boolean isShowCooldown() {
+        return node.getNode("show-cooldown").getBoolean(true);
+    }
+
     @Override
     public String getDefaultLocale() {
         return node.getNode("default-locale").getString("en_us");