add load connections form

[calebdoxsey]

Summary

This adds a new form to load connections from a Pomerium URL using the new routes discovery portal. TCP and UDP connections will be created automatically.

I attempted to make it preserve any manually edited settings that aren't directly set by the load form (like the listener address).

The Load Form has an advanced section similar to the regular form. Those connection options will be used for each of the created connections. (For example to disable TLS)

The inputs on this form are saved into local storage so the user can reload their connections quickly.

Other changes:

• the API protobuf was regenerated based on changes from routes: add routes list command cli#487
• I noticed while testing that loading the routes was a little racy, so I added some async helpers so we can wait for the save to complete before reloading all the routes again
• The "New Connection" button was changed into a pop-over. This was mostly copied from the zero ui.
• I pulled out the TagSelector into a component
• I added some spacing between the header and forms on some of the pages. The buttons seemed to close to the border of the form.

Related issues

• Fixes ENG-1879

Checklist

• reference any related issues
• updated docs
• updated unit tests
• updated UPGRADING.md
• add appropriate tag (improvement / bug / etc)
• ready for review

[nhayfield]

Is most of this prettier updates?

[nhayfield]

After reviewing individual commits this makes more sense.