REFACTOR: Move app-events:main to service:app-events (#8152)

AppEvents was always a service object in disguise, so we should move it
to the correct place in the application. Doing this allows other service
objects to inject it easily without container access.

In the future we should also deprecate `this.appEvents` without an
explicit injection too.

test/javascripts/components/d-editor-test.js.es6

@@ -704,7 +704,7 @@ testCase("replace-text event by default", async function(assert) {
   this.set("value", "red green blue");
 
   await this.container
-    .lookup("app-events:main")
+    .lookup("service:app-events")
     .trigger("composer:replace-text", "green", "yellow");
 
   assert.equal(this.value, "red green blue");
@@ -714,7 +714,7 @@ composerTestCase("replace-text event for composer", async function(assert) {
   this.set("value", "red green blue");
 
   await this.container
-    .lookup("app-events:main")
+    .lookup("service:app-events")
     .trigger("composer:replace-text", "green", "yellow");
 
   assert.equal(this.value, "red yellow blue");
@@ -800,7 +800,7 @@ composerTestCase("replace-text event for composer", async function(assert) {
       setTextareaSelection(textarea, start, start + len);
 
       this.container
-        .lookup("app-events:main")
+        .lookup("service:app-events")
         .trigger("composer:replace-text", "green", "yellow", { forceFocus: true });
 
       Ember.run.next(() => {