Support env, env_file for Azure Function

[GKotfis]

What should we add or change to make your life better?

Add support for env, env_file for azureFunction service

Why is this important to you?

Right now, there is no option to pass any env variables to az function.
I tried to declare it such way:

name: az-functions
services:
- name: my-func
  azureFunction: api/MyFunction
  env_file:
    - env_shared.env

but this leads to an error:

Drats! 'run' failed:
        Unable to determine service type.

Also tried with env - getting same error.

[philliphoff]

Closing per #1171.