remove app-config and feature flag implementation

[drewvolz]

This changeset accomplishes the following

• Removes two rerenders of the Home Screen view
• Removes experimentation around showing different course search initial views
• Removes modules/app-config
• Removes support for feature flags

If this were to be brought back, the hope would be for a rewrite to:

1. Prioritize performance
2. Use Zustand instead of Tanstack
3. Fit a need for testing out changes that we don't already have with debug builds