Tag for definening default services, and listing of services

[jornhd]

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

1. It would be nice to be able to define which services that runs when you write tye run.
   To enable this, I suggest that only services tagged with default should run when not specifying tags, as long as any default tag exist.

2. Suggest a new command services to list all available services. This should also have the option --tags that displays a list of available tags for each service.

Why is this important to you?

1. Mainly we reference the dependent services deployed on server when developing, but sometimes we need to run some of these dependent services locally. Then it's great to already have set them up in tye.yaml so we can specify the needed services with the --tags option. At the end of the day, we would like that tye run would act as tye run --tags default.

2. Yes, you can get the same info with notepad tye.yaml, but with the suggested command it's much more readable and easier for developers that is not used to read yaml.