Co-located component template files

no issue

Keeps component JS backing files and template files in the same directory which avoids hunting across directories when working with components. Also lets you see all components when looking at one directory, whereas previously template-only or js-only components may not have been obvious without looking at both directories.

- ran [codemod](https://github.com/ember-codemods/ember-component-template-colocation-migrator/) for app-level components
- manually moved in-repo-addon component templates in `lib/koenig-editor`
- removed all explicit `layout` imports as JS/template associations are now made at build-time removing the need for them
- updated `.embercli` to default to new flat component structure

ghost/admin/.ember-cli

@@ -1,4 +1,6 @@
 {
+    "component-structure": "flat",
+    "component-class": "@glimmer/component",
     /**
         Ember CLI sends analytics information by default. The data is completely
         anonymous, but there are times when you might want to disable this behavior.

ghost/admin/app/components/gh-basic-dropdown.js

@@ -1,9 +1,6 @@
 import BasicDropdown from 'ember-basic-dropdown/components/basic-dropdown';
-import templateLayout from '../templates/components/gh-basic-dropdown';
-import {layout} from '@ember-decorators/component';
 import {inject as service} from '@ember/service';
 
-@layout(templateLayout)
 class GhBasicDropdown extends BasicDropdown {
     @service dropdown
 

ghost/admin/app/components/gh-infinity-loader.js

@@ -1,6 +1,3 @@
 import InfinityLoader from 'ember-infinity/components/infinity-loader';
-import layout from '../templates/components/gh-infinity-loader';
 
-export default InfinityLoader.extend({
-    layout
-});
+export default InfinityLoader.extend();

ghost/admin/app/components/gh-power-select/trigger.js

@@ -1,8 +1,5 @@
 import PowerSelectTrigger from 'ember-power-select/components/power-select/trigger';
-import templateLayout from '../../templates/components/gh-power-select/trigger';
-import {layout} from '@ember-decorators/component';
 
-@layout(templateLayout)
 export default class Trigger extends PowerSelectTrigger {
 
 }

ghost/admin/app/components/gh-token-input/select-multiple.js

@@ -1,9 +1,8 @@
 import $ from 'jquery';
 import PowerSelectMultiple from 'ember-power-select/components/power-select-multiple';
-import templateLayout from '../../templates/components/gh-token-input/select-multiple';
 import {action} from '@ember/object';
 import {bind} from '@ember/runloop';
-import {layout, tagName} from '@ember-decorators/component';
+import {tagName} from '@ember-decorators/component';
 
 // TODO: convert from jQuery to native DOM
 const END_ACTIONS = 'click.ghToken mouseup.ghToken touchend.ghToken';
@@ -14,7 +13,6 @@ const END_ACTIONS = 'click.ghToken mouseup.ghToken touchend.ghToken';
 // we get another event signalling the end of a drag
 
 @tagName('div')
-@layout(templateLayout)
 class GhTokenInputSelectMultiple extends PowerSelectMultiple {
     _canFocus = true;