Moves the chat service public APIs to use uris for identifying sessions instead of ids. These uris are preferred as they work correctly for both contributed and local session

This ends up touch a lot of the chat apis. In most cases, the change is simply to pass in the URI instead of the id. In a few cases where the URI hasn't been fully hooked up, I am using `LocalChatSessionUri` to do this conversation

For the chat session implementation, I also switched to use resource maps to store session specific information instead of a normal map