Added support for targeted messages

[rodrigobr-msft]

This pull request adds support for "activity treatment" entities to the Microsoft Agents Activity library, improves the handling and serialization of entity types, and introduces some tests for these features. The most important changes are grouped below:

Activity Treatment Entity Support

• Introduced the ActivityTreatment entity and its type enum ActivityTreatmentType, allowing activities to specify treatment information such as targeted delivery. (activity_treatment.py, __init__.py) [1] [2]
• Added the get_activity_treatments method to the Activity class to easily retrieve all activity treatment entities from an activity. (activity.py)

Entity Type Improvements

• Added the EntityTypes class to centralize entity type string constants (e.g., "mention", "activitytreatment"), and updated entity classes to use these constants for type assignment. (entity.py, mention.py, __init__.py) [1] [2] [3] [4]
• Updated imports throughout the codebase to use the new EntityTypes class. (__init__.py, activity.py, mention.py) [1] [2] [3] [4]

Testing and Serialization

• Added new tests for entity extraction methods (get_mentions, get_activity_treatments) and for serialization/deserialization of Mention and ActivityTreatment entities, ensuring correct handling and compatibility with generic Entity objects. (test_activity.py, test_entities.py) [1] [2]

These changes enhance the extensibility and reliability of the activity entity system, making it easier to work with new entity types and ensuring robust serialization and extraction logic.

[tracyboehrer]

@axelsrz , @rodrigobr-msft , @MattB-msft We might need to talk about this. The last time I talked to the Teams guy doing this, they felt this needed to be done through new TeamsConnectorClient operation instead of this structure. Matt, do you have a different understanding?