Support EBS Task Attach non-root user mode

[kiryl1]

Summary

Enables running ECS EC2 Tasks with EBS Task Attach Enabled as a Non Root User. The change allows the Non Root User inside of the running container to write to the attached EBS Volume.

Implementation details

• For each container with EBSTA mounts, the Agent generates the appropriate GID
• The GID is deterministically generated from the volume's SourceVolumeHostPath
• The GID is added as a supplementary group to the container process via Docker's --group-add
• After the CSI driver completes mounting the volume in NodeStageVolume, sets the mount point ownership to this GID using chown and sets permissions to 775 with setgid bit using chmod
• Advertise a new agent capability ecs.capability.storage.ebsta-non-root-user during instance registration. This helps ECS back-end find a capable instance during task placement.

Testing

New tests cover the changes: Yes

• Updated existing and added new unit tests.
• New functional E2E tests to come next.

Description for the changelog

Feature: Support EBS task attach non-root user mode

Additional Information

Does this PR include breaking model changes? If so, Have you added transformation functions? No

Does this PR include the addition of new environment variables in the README? No

Licensing

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[singholt]

Dont forget to squash your commits when merging this PR.