chore: Don't transform Observation shape from server

[gmaclennan]

For historical reasons, we transform the observation received from the server to a different shape for use within the app. This makes it harder to share code between mobile and desktop and is confusing for developers. (It was a short-term short-cut dating back to when the two apps were developed separately and we had not agreed on a schema for Mapeo, so it was easier than re-writing).

With all the flow types in place it should be relatively easy to remove the transform and adjust all the components to accept the Observation shape as exported from mapeo-schema