Beta tab initial test for E2E, needs styled

packages/builder/src/components/beta/BetaTab.svelte

@@ -1,13 +1,13 @@
 <script>
   import { Body, Button, Layout, Heading } from "@budibase/bbui"
-  import { CookieUtils } from "@budibase/frontend-core"
+  import { flags } from "stores/backend"
 
   function openFeedbackApp() {
     window.open(`https://bb.budibase.app/betauifeedback`)
   }
 
-  function revertToOldBuilder() {
-    CookieUtils.removeCookie("beta:new_design_ui")
+  async function revertToOldBuilder() {
+    await flags.toggleUiFeature("design_ui")
     window.location.reload()
   }
 </script>

packages/builder/src/stores/backend/flags.js

@@ -16,6 +16,9 @@ export function createFlagsStore() {
       })
       await actions.fetch()
     },
+    toggleUiFeature: async feature => {
+      await API.toggleUiFeature({ value: feature })
+    },
   }
 
   return {

packages/frontend-core/src/api/flags.js

@@ -22,4 +22,13 @@ export const buildFlagEndpoints = API => ({
       },
     })
   },
+  /**
+   * Allows us to experimentally toggle a beta UI feature through a cookie.
+   * @param value the feature to toggle
+   */
+  toggleUiFeature: async ({ value }) => {
+    return await API.post({
+      url: `/api/beta/${value}`,
+    })
+  },
 })