API: support slug in the create workspace

[sananguliyev]

Tell us about the problem you're trying to solve

Since the name is not unique, we need to have something unique and human-readable. Fortunately, slug is exactly for that but it's not possible to control it. When the workspace name is the same, it's automatically suffixing some random string.

Describe the solution you’d like

Just support controlling slug

Describe the alternative you’ve considered or used

Alternatively, I am listing workspaces before creating one because it's not possible to know whether it will create slug as I expected or not.

Additional context

When we use some configuration for automation, it's ok to keep UUID for workspaces, but it would be perfect if we can make it better readable.

Are you willing to submit a PR?

Why not.