Fixes #minor

Description

This PR ports the changes from microsoft/botbuilder-dotnet#6564 to maintain parity with microsoft/botbuilder-dotnet.

This PR aims to extend the Bot SDK so that developers can consume newly added events that Teams will emit to the bot. They are:
TeamsMessageEdit - a user editing a message in Teams.
TeamsMessageUndelete - a user undo a deleted message in Teams.
TeamsMessageSoftDelete - a user soft deleting a message in Teams.

Specific Changes

1. Extended ActivityHandler to handle MessageUpdate and MessageDelete activity types and dispatch functions for activity types.
2. Extended TeamsActivityHandler to handle MessageUpdate (with subtypes TeamsMessageEdit and TeamsMessageUndelete) and MessageDelete (with subtype TeamsMessageSoftDelete) teams events.

ActivityHandler Class

• Added on_message_update_activity method and on_message_delete_activity method

TeamsActivityHandler Class

• Overrided the above two methods and add logic based to event_type
• on_message_update_activity could call on_teams_message_edit or on_teams_message_undelete
• on_message_delete_activity could call on_teams_message_soft_delete

Testing

The following images shows the related unit test passing.