[packager] Add minisite_url and primary_script to template yaml

I have this error using packager;
`google.protobuf.text_format.ParseError: 43:1 : Message type "google.fonts_public.FamilyProto" has no field named "minisite_url".`

So I guess 2 things:
- the protobuf format should be updated so packager stop having this error
- I added the minisite_url manually, but should be possible to do it from the template yaml. Same with primary script.