Implement the archived attribute on Project data source and resource

[dihedron]

Hallo, I'm proposing in this PR a few changes to enable the management of the archived attribute on both the gitlab_project resource and data source.
In doing so I had to implement partial state update in the project's update method, since the existing project properties update logic and the new archiving/unarchiving operation require different API calls, which may fail independently.
In the process I also noticed that the existing code to handle the shared_with_groups attribute in the gitlab_project resource method does not seem to handle errors which are swallowed altogether. Since this attribute, just like the archived attribute, requires its own different API call, I expected it to use partial state updates in order to avoid an inconsistent state in case of failure.
I updated the acceptance tests and the documentation for both resource and datasource.
Hope this helps!

[roidelapluie]

Hello,

SetPartial is great and could be used in create too ?

[dihedron]

I'll check about that!

[dihedron]

SetPartial is great and could be used in create too?

OK, as far as I understand, the resource is only committed to Terraform state once you set its ID in the schema.ResourceData, which happens quite (maybe too?) late in the resourceGitlabProjectCreate function.

Partial state management shoud still fit in but I feel it is more effective if we move this line:

d.SetId(fmt.Sprintf("%d", project.ID))

above the shared_with_groups update code, like this:

	// from this point onwards no matter how we return, resource creation 
	// is committed to state since we set its ID
	d.SetId(fmt.Sprintf("%d", project.ID))

	if v, ok := d.GetOk("shared_with_groups"); ok {
		for _, option := range expandSharedWithGroupsOptions(v) {
			if _, err := client.Projects.ShareProjectWithGroup(project.ID, option); err != nil {
				return err
			}
		}
		d.SetPartial("shared_with_groups")
	}

This is a change to code I didn't write and I'd like your advice on this before I submit it. Let me know.
Cheers!

[roidelapluie]

Fine for me!

[dihedron]

OK, it's in the PR.
While testing that shared_with_groups was unaffected by my changes, I noticed the docs reported the groups_access_level as optional whereas it's Required: true in the schema. I fixed the docs, it's in the same PR.
Cheers.