[Compute usage quotas]: Develop frontend of JupyterHub service for users to check usage and quota limits

[jnywong]

Definition of done

• Implement design from [Compute usage quotas]: Create UI mockup of JupyterHub service #7501
• Gather one round of feedback from the community
• Incorporate feedback into an iteration of the design

[jnywong]

This is pretty much done pending #7502 where there will be a config option to include a custom message for admins to present to end users re: point 4 in this comment

[jnywong]

I'm calling this one complete. The custom config message can be added later.