Use LoadingCache instead of a regular map + more datastore fixes

bukkit/src/main/java/me/lucko/luckperms/bukkit/LPBukkitPlugin.java

@@ -198,7 +198,7 @@ public class LPBukkitPlugin extends JavaPlugin implements LuckPermsPlugin {
     public void onDisable() {
         started = false;
         getLog().info("Closing datastore...");
-        datastore.shutdown().getOrDefault(null);
+        datastore.shutdown();
 
         getLog().info("Unregistering API...");
         ApiHandler.unregisterProvider();

bukkit/src/main/java/me/lucko/luckperms/bukkit/inject/LPPermissible.java

@@ -222,7 +222,7 @@ public class LPPermissible extends PermissibleBase {
         }
 
         if (hasData()) {
-            user.getUserData().invalidateCache();
+            user.getUserData().invalidatePermissionCalculators();
         }
     }