No language selection for nested Function Apps

[ankitkumarr]

1. func init (Select a language L)
2. mkdir nestedApp
3. cd nestedApp
4. func init (func assumes the language to be L)

We should maybe throw an error for nested Function Apps or at the least not assume a worker runtime.

This should be a low-pri item as this isn't a blocking scenario and ideally users shouldn't be hitting this case.

cc: @ColbyTresness