Editor embeds (#680)

- [x] Make deleting an embed easier
- [x] Add document level ability to disable embeds
- [x] Add team level ability to disable embeds
- [x] GitHub
- [x] Numeracy
- [x] Mode Analytics
- [x] Figma
- [x] Airtable
- [x] Vimeo
- [x] RealtimeBoard
- [x] Loom
- [x] Lucidcharts
- [x] Framer
- [x] InVision
- [x] Typeform
- [x] Marvel
- [x] Spotify
- [x] Codepen
- [x] Trello

app/embeds/Gist.test.js

@@ -0,0 +1,19 @@
+/* eslint-disable flowtype/require-valid-file-annotation */
+import embeds from '.';
+
+const { Gist } = embeds;
+
+describe('Gist', () => {
+  const match = Gist.ENABLED[0];
+  test('to be enabled on gist link', () => {
+    expect(
+      'https://gist.github.com/wmertens/0b4fd66ca7055fd290ecc4b9d95271a9'.match(
+        match
+      )
+    ).toBeTruthy();
+  });
+
+  test('to not be enabled elsewhere', () => {
+    expect('https://gist.github.com/tommoor'.match(match)).toBe(null);
+  });
+});