Summary: As part of restoring a continuous backup we should also restore any releases that are present in the S3 bucket but not locally. This diff downloads the remote releases to a local directory inside of /opt/yugabyte/releases/<version> as part of every restore continuous backup execution.

Test Plan:
remove local release that was uploaded to s3 bucket
run restore continuous backup, ensure releases get downloaded

Reviewers: dshubin, svarshney, vkumar

Subscribers: yugaware

Differential Revision: https://phorge.dev.yugabyte.com/D40573