Register tasks earlier

@jnehlmeier noticed that it can be difficult to create other settings
plugins that build off the tag/push tasks that reckon registers due to
them being registered after projectLoaded.

Since these are only added to the root project, its a trivial tweak to
just register directly on rootProject and avoid the extra ordering
confusion for downstream authors.

Fixes #200

reckon-gradle/src/main/java/org/ajoberstar/reckon/gradle/ReckonSettingsPlugin.java

@@ -36,9 +36,9 @@ public void apply(Settings settings) {
       prj.setVersion(sharedVersion);
     });
 
-    settings.getGradle().projectsLoaded(gradle -> {
-      var tag = createTagTask(settings.getGradle().getRootProject(), extension);
-      var push = createPushTask(settings.getGradle().getRootProject(), extension);
+    settings.getGradle().rootProject(rootProject -> {
+      var tag = createTagTask(rootProject, extension);
+      var push = createPushTask(rootProject, extension);
       push.configure(t -> t.dependsOn(tag));
     });
   }