DEV: ember-cli refactor for TextField and TextArea imports (#9480)

In order to be able to use ember-cli we need to fix the import
statements for `TextField` and `TextArea` in the code base.

The only change I don't fully understand is the one in
`discourse-loader.js`, but adding the components to that file make it
all work.

app/assets/javascripts/discourse-loader.js

@@ -19,9 +19,7 @@ var define, requirejs;
         default: Ember.ArrayProxy
       },
       "@ember/component": {
-        default: Ember.Component,
-        TextArea: Ember.TextArea,
-        TextField: Ember.TextField
+        default: Ember.Component
       },
       "@ember/controller": {
         default: Ember.Controller,
@@ -129,6 +127,12 @@ var define, requirejs;
       "@ember/component/helper": {
         default: Ember.Helper
       },
+      "@ember/component/text-field": {
+        default: Ember.TextField
+      },
+      "@ember/component/text-area": {
+        default: Ember.TextArea
+      },
       "@ember/error": {
         default: Ember.error
       },

app/assets/javascripts/discourse/app/components/expanding-text-area.js

@@ -1,4 +1,4 @@
-import { TextArea } from "@ember/component";
+import TextArea from "@ember/component/text-area";
 import { schedule } from "@ember/runloop";
 import { on, observes } from "discourse-common/utils/decorators";
 import autosize from "discourse/lib/autosize";

app/assets/javascripts/discourse/app/components/honeypot-input.js

@@ -1,4 +1,4 @@
-import { TextField } from "@ember/component";
+import TextField from "discourse/components/text-field";
 import { on } from "discourse-common/utils/decorators";
 
 export default TextField.extend({

app/assets/javascripts/discourse/app/components/number-field.js

@@ -1,4 +1,4 @@
-import { TextField } from "@ember/component";
+import TextField from "discourse/components/text-field";
 import discourseComputed from "discourse-common/utils/decorators";
 
 export default TextField.extend({

app/assets/javascripts/discourse/app/components/text-field.js

@@ -1,4 +1,4 @@
-import { TextField } from "@ember/component";
+import TextField from "@ember/component/text-field";
 import discourseComputed from "discourse-common/utils/decorators";
 import { siteDir, isRTL, isLTR } from "discourse/lib/text-direction";
 import { next, debounce, cancel } from "@ember/runloop";