azure.ai.agents - show status of RBAC roles of the agent with `azd ai agent show`

The postdeploy hooks in the extension attempt to check for an agent identity and assign RBAC roles that are needed for the agent to use Foundry Project resources like a model, etc.

If those fail for some reason (permissions, etc.), its not clear to the user and it's hard to check after a deploy if it worked or not. We can add output to the deploy below the portal links that summarizes if the roles were successful or not, and also include this information in the `show` output.

Otherwise devs will get errors like this: