provide interception rewrites to edge runtime (#61414)
In #61794, the routes manifest is used to find the interception route rewrites in `next-server` and computed on the fly in `next-dev-server` based on `appPaths`.
The edge runtime doesn't have access to the routes manifest nor a full list of app paths. This writes an entry for the edge runtime to make the interception routes readable, and adds plumbing to return them in the `getInterceptionRouteRewrites` handling in `web-server`. This is what we use to signal to the server whether to return ‘Next-URL’ in the Vary for RSC requests.
This piggybacks on the existing interception routes test but adds an edge runtime case.
Closes NEXT-2304
