Allow users to subscribe to our newsletter

[xiaofei-du]

If a user set newsletter_subscription as true, subscribe the user to our newsletter.

If an error is returned from subscribing operation, the console needs to handle the error internally, no need to show it on the UI.

[EiffelFly]

@xiaofei-du After looking up the old implementation we have at product-webiste, this feature may have a issue

• It need to use MAILCHIMP_API_KEY to access the Mailchimp API, this key need to be private.
  • For local dev we don't have any storage solution that can guarantee the safety of our key

Solution

• We need to setup a serverless lambda function using cloudflare or aws lambda to act as the relay.
  • The console will send request to the serverless function, and the function will use stored API_KEY to access Mailchimp API

[xiaofei-du]

We will use another workaround to solve this.