Updates launcher_atom.proto to support consistent logging for launcher containers.

* Updated default of some fields to invalid values. Because when these fields are not actually set on the client, the default values could lead to misinterpretations on the server side.
* Refactored container messages into a separate oneof message to use it on the client side as interface.

Test: Manual (make NexusLauncherDebug -j100)
Bug: 144124838

Change-Id: I2d2ea05e9d7d043682d8ca1a56a238d9d22174bb