Add support for FUNCTIONS_WORKER_RUNTIME in host.json

[pragnagopa]

host.json should support FUNCTIONS_WORKER_RUNTIME setting. Right now the CLI uses that setting for figuring out your app's type, since many operations (init, new, start, publish, etc) are language specific. Currently that is stored in local.settings.json which is not committed in the repo.

[pragnagopa]

@paulbatum @ahmelsayed

[fabiocav]

This needs additional discussion with @pragnagopa @ahmelsayed @mathewc

[ahmelsayed]

as Pragna mentioned. the main issue currently is that the CLI used that value to figure out how to build, run, and publish the app. However, since that setting is stored in local.settings.json which doesn't make it to source control, it makes the experience a bit odd especially for things like CIs or when you clone a new project

[EddieDL]

@ahmelsayed How do you deal with this issue on CI, or multiple developer environments? It seems like there isn't any real solution and we just need to train/document what setting it should be.