Add missing unit tests

[goncalo-rodrigues]

Add unit tests for resource_metadata:

• importing config - make sure everything is added and GetAffectedResources returns what's expected
• exporting config
• creating resource - make sure that resource groups are created
• delete resource - make sure resource groups are deleted by default
• create child resources should use the same resource group id when possible

Add unit tests for grpc:

• make sure config is read and written
• make sure init and apply are always called

Add unit tests for deploy:

• make sure exec.command is called with the appropriate parameters