Add CLI flag to select pipelines to execute

[georg-schwarz]

Required for #587

[rhazn]

Ah failed to comment on the review on Mobile, but: I think the approach is weird to make it a required parameter with a default value. I think it would be better as an optional parameter and if it's undefined, run all pipelines. But I don't mind that much, so your choice.

[joluj]

I think the approach is weird to make it a required parameter with a default value.

Isn't that often like that? The default is running all pipelines, so I think that's fine.
It saves us a bit of complexity to know that the string cannot be undefined

[rhazn]

Yeah, that's why I don't mind as much. But it will lead to some weird errors down the line when you write "can't find a pipeline for .*" and the user is confused because they never entered that. I know that is not how it would work right now, but by giving it a default value and then using that value later on in error messages, this kind of stuff can happen.

But as I said, I think that is a real edge case and I am happy with this as well.