Setup profile tabs in Vue

What does this MR do and why?

Related to #378688 (closed)

We are starting the process of migrating the tabs on the user profile from HAML to Vue. This migration will be split across a number of issues/MRs and is being managed in &9056

This MR setups the Vue app and the tabs but doesn't actually render anything in any of the tabs. There is an issue for each tab in &9056. Each tab will be built out individually in future MRs. This is behind the profile_tabs_vue feature flag.

Screenshots or screen recordings

Feature flag disabled	Feature flag enabled

How to set up and validate locally

1. Enable the profile_tabs_vue feature flag
   • bin/rails console
   • Feature.enable(:profile_tabs_vue)
2. Navigate to your profile

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.