Tenant-based visibility control for Activities in Workflow Studio

## Feature Request

### Problem Overview
In the Workflow Studio editor, the left-hand Activities menu currently shows all available activities to every tenant and developer.
This creates challenges in multi-tenant or enterprise environments:

Some activities should not be visible to certain developer groups (e.g., experimental, admin-only, or restricted integrations).

Lack of control over which activities are shown leads to confusion and potential misuse.

At present, there is no mechanism to control visibility of activities per tenant or per role/group.

### Proposed Solution
Introduce support for tenant-based (or role-based) activity visibility control.

### Alternative Solutions
Currently, the only workaround is to modify/customize the codebase, which is not sustainable.

### Use Cases
Tenant A: should only see standard activities (HTTP, Flow, Console).
Tenant B: should have access to custom activities like ERP, AI, or external integrations.
Admin developers: can see all activities, including experimental or beta ones.

### Impact of Feature
Improves security by preventing unauthorized usage of certain activities.
Reduces complexity for developers by showing only relevant activities.