Require navigation changes to be approved by a foundations engineer

What does this MR do and why?

This MR updates the codeowners file to block any navigation changes without approval from a groupfoundations engineer. This was already a formal process outlined in the handbook, this change draws more attention to it and ensures nothing slips through the cracks.

I've set this to be approved by an engineer as they are more likely to understand what the change entails, but it is ultimately a product decision as to whether a navigational change can be made.

From @cdybenko in Slack:

Given our goal of improving SUS with navigation, we have to be sure that all navigation changes are vetted and discussed.

Current rules/process:

• We are NOT allowing any top level navigation additions to protect our new design
• Any sub menu item must follow this process and get approval from me as the DRI on this issue template
• Review will happen by the product designers on our team and hopefully they will present their solution AND UXR to their suggestion We will need a new process to ensure that all newly added items are checked by eng to ensure they have the right tracking added We’ll need to keep evangelizing this process throughout product/engineering

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.