Mainification: Bring Onboarding in from rh-test (#6564)

## Summary

Migrate the onboarding / login / sign-up / survey pieces from `rh-test`
to `main`.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6564-WIP-Bring-Onboarding-in-from-rh-test-2a16d73d365081318483f993e3ca0f89)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Jin Yi <jin12cc@gmail.com>
Co-authored-by: GitHub Action <action@github.com>

src/platform/telemetry/providers/cloud/MixpanelTelemetryProvider.ts

@@ -146,6 +146,10 @@ export class MixpanelTelemetryProvider implements TelemetryProvider {
     }
   }
 
+  trackSignupOpened(): void {
+    this.trackEvent(TelemetryEvents.USER_SIGN_UP_OPENED)
+  }
+
   trackAuth(metadata: AuthMetadata): void {
     this.trackEvent(TelemetryEvents.USER_AUTH_COMPLETED, metadata)
   }

src/platform/telemetry/types.ts

@@ -258,6 +258,7 @@ export interface WorkflowCreatedMetadata {
  */
 export interface TelemetryProvider {
   // Authentication flow events
+  trackSignupOpened(): void
   trackAuth(metadata: AuthMetadata): void
   trackUserLoggedIn(): void
 
@@ -334,6 +335,7 @@ export interface TelemetryProvider {
  */
 export const TelemetryEvents = {
   // Authentication Flow
+  USER_SIGN_UP_OPENED: 'app:user_sign_up_opened',
   USER_AUTH_COMPLETED: 'app:user_auth_completed',
   USER_LOGGED_IN: 'app:user_logged_in',