refactor(helpers): separate functions into files (#667)

* refactor(helpers): separate functions into files

* idk

* idk

src/helpers/channels/follow_channel.ts

@@ -0,0 +1,21 @@
+import { RequestManager } from "../../rest/request_manager.ts";
+import { FollowedChannelPayload } from "../../types/mod.ts";
+import { endpoints } from "../../util/constants.ts";
+import { requireBotChannelPermissions } from "../../util/permissions.ts";
+
+/** Follow a News Channel to send messages to a target channel. Requires the `MANAGE_WEBHOOKS` permission in the target channel. Returns the webhook id. */
+export async function followChannel(
+  sourceChannelID: string,
+  targetChannelID: string,
+) {
+  await requireBotChannelPermissions(targetChannelID, ["MANAGE_WEBHOOKS"]);
+
+  const data = (await RequestManager.post(
+    endpoints.CHANNEL_FOLLOW(sourceChannelID),
+    {
+      webhook_channel_id: targetChannelID,
+    },
+  )) as FollowedChannelPayload;
+
+  return data.webhook_id;
+}