Support for Multiple Application Scopes (Agents) within a single window process

## Enhancement Request

This enhancement is looking at the problem from a web perspective but could be extended to other implementing technologies.

### Use Case:
As more web applications adopt micro-frontend architecture, users often encounter scenarios where multiple application contexts need to be loaded into a single window process through dynamic code resolution techniques like module federation. Currently, the FDC spec assumes a one-to-one mapping between Window, Agent, and Application, which limits the ability to handle multiple application contexts within a single window. This creates challenges for users who need to interact with different application scopes seamlessly within the same window environment.

### Workflow Description
The proposed enhancement involves updating the FDC spec to support the creation of Agents with different application scopes within a single window process. This would allow multiple micro-frontends applications to coexist and interact within the same window, providing a more flexible and efficient user experience. The workflow should enable dynamic resolution and management of multiple Agents, each corresponding to different applications, within a single window context.

### Workflow Examples

**Multi-tool Dashboard**

- A user accesses a dashboard that integrates multiple tools (e.g., a calendar, email client, and task manager) using micro-frontend architecture.
- Each tool operates as a separate application deployed remotely from the container however will share the context within the same window.
- The enhanced FDC spec allows each tool to create and manage its own Agent within the same window, enabling seamless interaction and communication between the tools.

### Additional Information
Supporting the creation of Agents with different application scopes within a single window process would significantly enhance the flexibility and usability of applications using micro-frontend architecture. This enhancement would reduce the need for redundant window processes, streamline resource management, and improve the overall user experience by enabling more dynamic and integrated interactions between multiple application contexts.

Start by reviewing the FDC spec's current one-to-one Window, Agent, and Application model and the workflow examples in this issue. Identify the affected specification sections and establish acceptance criteria for multiple application scopes in one window; done requires an agreed spec change and corresponding validation.

Written by the indexing model from the issue text.