[Workspace] Only OSD admin can create workspace

[yubonluo]

Is your feature request related to a problem? Please describe.
With workspace feature enabled, saved objects permission control enabled and security plugin installed, only OSD admin(#6389) can create workspace. If permission control is closed, anyone has the permission to create workspace.

Describe the solution you'd like
Before creating a workspace, saved objects wrapper will verify if the user/group is the OSD admin.

Additional context
#4944

[BionIT]

Hi @yubonluo, is this issue for 2.15 or 2.16?

[yubonluo]

Hi @yubonluo, is this issue for 2.15 or 2.16?

Hi @BionIT this issue is for 2.15.