DRY up workspace owner state fetching for workspace creation & dynamic params

[Emyrk]

getWorkspaceOwnerData for dynamic parameters is supposed to mirror how provisionerd injects user state.

See:

• https://github.com/coder/coder/blob/5816455207edeb3763b8af7547ec74fcaa69e363/coderd/provisionerdserver/provisionerdserver.go#L641-L641
• https://github.com/coder/coder/blob/5816455207edeb3763b8af7547ec74fcaa69e363/coderd/provisionerdserver/provisionerdserver.go#L697-L701

This should ideally be the exact same method/function