fix: scope autohooks setNotFoundHandler under prefixed autoload

[SergioChan]

Summary

• scope autohooks registration under a shared plugin prefix when all plugins in the node resolve to the same prefix
• strip that shared prefix from child plugin registrations inside the scoped context so routes are not double-prefixed
• add a regression test for issue setNotFoundHandler is not encapsulated when called inside autohooks.js #326 proving setNotFoundHandler from autohooks.js only affects /api/* requests

Testing

• npm run unit test/issues/326/test.js test/issues/374/test.js test/issues/376/test.js test/issues/453/test.js

Related

Fixes #326

[mcollina]

lgtm