Migrate unified-logviewer to a standalone React component

[eliperelman]

To relieve some CORS and hosting issues, the Unified Logviewer needs to move away from being hosted in an iframe on GitHub pages, and into a standalone React component that can be imported into the relevant application. Depends on #25.

[eliperelman]

Associated repo: https://github.com/mozilla-rpweb/react-lazylog

[gregarndt]

Next piece to complete is integrating it within the inspector

[eliperelman]

Inspector integration complete.

[djmitche]

This RFC is stored as rfcs/0027-Migrate-unified-logviewer-to-a-standalone-React-component.md