Chat Fixes and Improvements

[mdmohsin7]

Part of #1414

• There are no user sent messages for the omi app if I close and open the main app
• Apps send two initial messages instead of one

[beastoin]

lgtm @mdmohsin7 🥳

also what is the root cause of null, no_select ? 🫢

[mdmohsin7]

The issue was that when no plugin id was being passed, the backend was receiving "null" (string) as the plugin_id and it was storing the same in firestore. So when you try to fetch messages from the db it will try to fetch all the messages with plugin_id value as null, but the user sent messages have the value "null", hence they were never returned by the db @beastoin