ECS Anywhere install script fixups
ECS Anywhere install script fixups

- check curl downloads for failures (404, 403, etc.)
- log what script is doing while waiting for agent to startup
- change wording around agent startup wait
- add license info for ssm agent and docker engine
- a couple shellcheck fixes

kiranmeduri/amazon-ecs-agent,aws/amazon-ecs-init,aws/amazon-ecs-agent,aws/amazon-ecs-agent,aws/amazon-ecs-agent,kiranmeduri/amazon-ecs-agent,kiranmeduri/amazon-ecs-agent,aws/amazon-ecs-agent,kiranmeduri/amazon-ecs-agent,aws/amazon-ecs-init,aws/amazon-ecs-init