Share chat url

Modal for video owner (and instance's moderators) that allows to generate a link to the chat. So you can - for example - obtain the url to use for OBS integration.
WIP

client/videowatch/share.ts

@@ -0,0 +1,11 @@
+async function shareChatUrl ({ peertubeHelpers }: RegisterOptions): Promise<void> {
+  peertubeHelpers.showModal({
+    title: 'TODO',
+    content: '<p>TODO</p>',
+    close: true
+  })
+}
+
+export {
+  shareChatUrl
+}