feat: add guilds list in left sidebar

cypress/fixtures/guilds/get.ts

@@ -0,0 +1,15 @@
+import { Handler } from '../handler'
+
+import { guildExample, guildExample2 } from './guild'
+
+export const getGuildsHandler: Handler = {
+  method: 'GET',
+  url: '/guilds',
+  response: {
+    statusCode: 200,
+    body: [
+      { ...guildExample, defaultChannelId: 1 },
+      { ...guildExample2, defaultChannelId: 2 }
+    ]
+  }
+}