Webapp: Spike on Sourcegraph app UI extensibility

Created by: vovakulikov

Background

The Sourcegraph web app and some parts of it may run in different environments (code hosts, ide, web app itself) with different presets (open source, enterprise, trial ...). All this is handled by tuning props on the top-level component of the web app.

The current system isn't scalable. If we want to integrate different parts of the application, we should come up with a more reliable approach rather than having 100+ different top-level props.

This issue implies that the assignee of this will spike on this problem and do a small research on how it could be implemented differently. Taking into account RFC about project structure and package separation and further web app evolution.