Refactor app.js into per-component routes where appropriate

[caroqliu]

build-system/server/app.js is swelling in size. The good news is build-system/server/routes holds per-component routes. This issue is for tracking the effort of identifying any relevant endpoints in app.js attributed to specific component usage and pulling them into appropriately labeled files in the routes directory.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.