[comm-lib] Re-export AWS types

Summary:
This was one time suggested by Jon that until we have cargo workspace, we can have AWS dependencies inside comm-lib and use exports from there in our services.
This is a first step towards that.
Also removed unnecessary aws-types dependency, it is already included as a part of aws-config.

Test Plan: Services compile

Reviewers: michal, kamil, varun

Reviewed By: michal

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D10443