✨ Added "Gifs" card to the editor

refs https://github.com/TryGhost/Team/issues/1225

When inserted opens a searchable gif selector, creating an image card when a gif is chosen.

Includes keyboard navigation once open:
- `Tab`/`Shift+Tab` cycles highlighted gif through search result order
- `Up` / `Down` / `Left` / `Right` moves highlight in the respective direction
- `Enter` inserts highlighted gif

For the gifs card to be activated it's necessary to add a Tenor API key (obtained freely from https://tenor.com/gifapi) via your config.production.json file:

```
  ...
  "tenor": {
    "publicReadOnlyApiKey": "YOUR_KEY"
  }
}
```

ghost/admin/app/services/feature.js

@@ -63,7 +63,6 @@ export default Service.extend({
     calloutCard: feature('calloutCard', {developer: true}),
     nftCard: feature('nftCard', {developer: true}),
     accordionCard: feature('accordionCard', {developer: true}),
-    gifsCard: feature('gifsCard', {developer: true}),
     fileCard: feature('fileCard', {developer: true}),
     audioCard: feature('audioCard', {developer: true}),
     videoCard: feature('videoCard', {developer: true}),

ghost/admin/app/templates/settings/labs.hbs

@@ -378,19 +378,6 @@
                         </div>
                     </div>
                 </div>
-                <div class="gh-expandable-block">
-                    <div class="gh-expandable-header">
-                        <div>
-                            <h4 class="gh-expandable-title">Cardmageddon - Gifs</h4>
-                            <p class="gh-expandable-description">
-                                Adds a gif selector using Tenor for the image card
-                            </p>
-                        </div>
-                        <div class="for-switch">
-                           <GhFeatureFlag @flag="gifsCard" />
-                        </div>
-                    </div>
-                </div>
                 <div class="gh-expandable-block">
                     <div class="gh-expandable-header">
                         <div>

ghost/admin/lib/koenig-editor/addon/options/cards.js

@@ -190,7 +190,7 @@ export const CARD_MENU = [
             payload: {
                 imageSelector: 'tenor'
             },
-            isAvailable: ['feature.gifsCard', 'config.tenor.publicReadOnlyApiKey']
+            isAvailable: 'config.tenor.publicReadOnlyApiKey'
         },
         {
             label: 'Toggle',