[Workspace] Restrict unassigned data source access for non dashboard admin

[wanglam]

Is your feature request related to a problem? Please describe.

This is a feature request. Only dashboard admin can access unassigned data source saved objects after workspaces and savedObjects.permission enabled. For non dashboard admin users, they only can access assigned data sources in workspaces. For now, non dashboard admin can access unassigned data sources through the API directly.

Describe the solution you'd like

Modify the workspace permission saved object client wrapper, add specific logic to check if saved objects are unassigned data sources in the permission validation method. The permission validation method will be used in the RUD methods. For unassigned data sources, these methods will receive a navigate validation result and then will throw permission error.

Describe alternatives you've considered

N/A

Additional context

#4944