Add AdapativeCard support for Teams notification service.

Currently [Teams](https://argoproj.github.io/argo-rollouts/generated/notification-services/teams/) service uses "MessageCard" which is no longer supported by "Power Automate".
There is only one workaround - use [Webhook](https://argoproj.github.io/argo-rollouts/generated/notification-services/webhook/) service instead of "Teams", which is less convenient and flexible.

There is feature request - start supporting "AdapativeCard" for built-in Teams service.

Start with the built-in Teams notification service described in the linked Teams documentation, then compare it with the linked Webhook service. Identify the service entry point, configuration surface, and existing tests before defining the AdaptiveCard behavior; done means Power Automate can accept AdaptiveCard notifications through the Teams service.

Written by the indexing model from the issue text.