Use nft.json to resolve page dependencies

[ascorbic]

Currently we use a API route's nft.json files to trace dependencies for the function bundle. However we don't do this for the main handler and ODB functions. For these we instead trace all of the source files. This works in most cases, but means we miss some important files, particularly non-source files.

A good example is this test from #1773, which fails because we're not bundling the static hello.txt, even though it is in the nft.json file.

We should resolve dependencies for all routes in a similar way to how we do them for API routes. This would catch these cases.