Add aspire integration template

### Is there an existing issue for this?

- [X] I have searched the existing issues

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

Currently there's distinction between external components and internal projects, in a microservice setting you most likely don't have all the services inside the same solution. A "component template" or "external project" would fill this gap where a service is being developed that others can connect and interact with.

### Describe the solution you'd like

The template would be set up in such a way that it can be packaged for other services to depend on. Just like components, these services could be hosted locally or connect to a live instance.

### Additional context

Note this is a rough idea perhaps there's a way to do this today but I think it's worth considering it as a first-class building block.