bug with esbuild server port

[digitalsadhu]

occasionally, shutting down the server results in the esbuild server still locking its port. Running killall esbuild resolves this but it would be nice to anticipate and handle this within the podlet server.

[trygve-lie]

I think we should move the hot reload out of esbuild and into the fastify server it self. This will require a small change in how we listen and serve some files plus we will need to add a part which pushes hints about file changes.

I have actually written a plugin for this which we can add.