Restrict Upload of Common Layers to Admin Users Only

[robertohuru]

Description:

The current API implementation allows any authenticated user to upload common layers, which are primarily used as default global layers within the plugin. However, this poses a security and integrity concern, as these layers should be curated and managed only by users with administrative privileges.

Issue:

• Any authenticated user can currently upload common layers.
• Common layers serve as default global layers and should be centrally managed.
• The existing TrendsEarth role attribute is too generic and does not provide sufficient role-based access control to differentiate between standard users and administrators.

Expected Behavior:

• Only users with explicit administrative privileges should be allowed to upload or modify common layers.
• Standard authenticated users should be restricted from uploading or editing these layers.

@danangmassandy @zamuzakki