provisioner: merge galaxy config into common

[nywilken]

The Ansible galaxy arguments for both provisioners were duplicated among the provisioners although they are essentially the same.
Since they're the same, we move the common code and arguments into a common package so it can be reused between both provisioners.

[nywilken]

@SwampDragons this is where I got to on the refactor. Sharing in case you find anything usable.

[SwampDragons]

Thanks. I'll take a look at it when I have some downtime.

[hashicorp-cla]

All committers have signed the CLA.

[lbajolet-hashicorp]

Just a few nits/typos/questions, other than that LGTM, that's a good improvement

[lbajolet-hashicorp]

Ready for a review @nywilken

[nywilken]

Thanks for re-rolling this change. Overall it looks good. I left a suggestion on the BuildGalaxyArgs function to always return something.

[nywilken]

Return nil,nil feels like there is an error case we are missing. As it stands if we do return nil args with no error the execution of the args returned from BuildGalaxyArgs would fail. Would it be more appropriate to always return roleArgs or maybe an error if have no roles since the Galaxy file is invalid?

	// If collections keyword present (v2 format), install collections 
	if hasCollections {
		return collectionArgs, nil
	}
	
	// If roles keyword present (v2 format), or no collections keyword present (v1), install roles
	if hasRoles  {
		return roleArgs, nil
	}

	return nil, fmt.Errorf("messaging about the requirements file not containing any roles or collections")

Alternatively you can just return the roleArgs and let Ansible handle the errors

	// If collections keyword present (v2 format), install collections 
	if hasCollections {
		return collectionArgs, nil
	}

	return roleArgs, nil
	}

[lbajolet-hashicorp]

Agreed, I missed that one when adapting the code, but definitely that looks fishy, thanks for pointing it out