Adding meta-aws layer - Part 1

This MR concentrates on refactoring and cleanup of Cassini to modularise Cloud orchestration/service (K3s), to support Greengrass as cloud service

There are areas where the work is been done:

• CI - The K3s is a cloud orchestration, which is added to the base images like cassini, cassini-dev and cassini-sdk.Therefore rules needs to be clearer if the build triggers need to proceed for the changes specific to K3s files.
• Config and distro - K3s to be added a distro feature and can be included from k3s.yml
• K3s is not supported on Corstone-1000 so refactor and cleanup

Further, this also improves the boot time of Corstone1000-mps3 by 40 minutes in the CI.

--- Update ---

The meta-cassini-bsp is been separated into a different repository. Therefore MR - https://gitlab.arm.com/cassini/meta-cassini-bsp/-/merge_requests/4 is raised.

The concept of PREFERRED_RPROVIDER is been used as proposed.