Enhance `aspire update` so it can handle multi-apphost repos like Community Toolkit

The `aspire update` command (and the entire CLI) is mostly orientated towards operating on a single app host. In repos where there is multiple app hosts it does not work well. It updates a single app host and things it references and potentially CPM but leaves everything else which can leave things in a broken state.

We need to figure out how we are going to handle this scenario and what the workflow should be.

Start with the `aspire update` command and compare its behavior across the multiple app hosts in the Community Toolkit repository. Define the intended workflow for updating every app host and related dependencies, including CPM where applicable. Done means the multi-apphost workflow is agreed and no app host is left in a broken or outdated state.

Written by the indexing model from the issue text.