Webhooks can now be created, deleted, updated, or retrieved from the web

API.
Now that we have multiple sub-routers, (e.g. for repos/ and hooks/), the

router building code has been refactored into a data type (routingEntry)

and method (addRoutes) so that the same code does not need to be

repeated for each set of routes.
Co-authored-by: Florie Cai floriecai@hotmail.com

Ran go fmt ./....

Ran make test.

Ran make integration-tests.