[services] Lib - Move dynamo DB tools

Summary:
Depends on D3942

Moving the aws tools for dynamo DB to the "lib" space, so they can be used by all services that need the database access on AWS.

Test Plan:

cd services
yarn run-local-cloud
yarn test-backup-service-dev-mode
yarn test-blob-service-dev-mode

Reviewers: palys-swm, ashoat

Reviewed By: ashoat

Subscribers: ashoat, palys-swm, Adrian, atul, yayabosh

Differential Revision: https://phabricator.ashoat.com/D3943