Automatically notify GitLab.com users when our Privacy Policy/ToS are updated
### Problem to solve
Users need to be notified any time there is a change to our Privacy Policy or ToS.
### Intended users
<!-- Who will use this feature? If known, include any of the following: types of users (e.g. Developer), personas, or specific company roles (e.g. Release Manager). It's okay to write "Unknown" and fill this field in later.
Personas can be found at https://about.gitlab.com/handbook/marketing/product-marketing/roles-personas/ -->
GitLab.com (SaaS) users.
### Further details
<!-- Include use cases, benefits, and/or goals (contributes to our vision?) -->
We should consider how we handle this for Self-Managed customers.
### Proposal
<!-- How are we going to solve the problem? Try to include the user journey! https://about.gitlab.com/handbook/journeys/#user-journey -->
Whenever an update is made to our Privacy Policy page or ToS in the handbook, we should automatically notify users in-app via a CTA banner linking to the privacy policy and ToS.
https://about.gitlab.com/privacy/
Related issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/64341
cc @gweaver @nick.thomas @cciresi @MFarber
issue