Extension bundle is required for hot reload

Example at https://github.com/pellebjerkestrand/azure-functions-core-tools-restart-bug

Using JavaScript with programming model 4, changes to app code are not reflected while the server is running.

Start with the linked reproduction repository and its JavaScript programming model 4 app, then run the server and change app code to observe whether updates are reflected. Trace how the host handles hot reload and extension bundles; done means app-code changes are picked up while the server remains running without requiring the extension bundle.

Written by the indexing model from the issue text.