[ECS] [Feature Request]: ECS Anywhere support for EFS - amazon-ecs-volume plugin

**Tell us about your request**
What do you want us to build?
Would like to make use of `efsVolumeConfiguration` when making use of ECS Anywhere.
**Which service(s) is this request for?**
ECS Anywhere.

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
Trying to make use of the amazon-ecs-volume plugin to mount EFS into a task running on an external instance.

**Are you currently working around this issue?**
How are you currently solving this problem?
By installing the volume driver manually as per the suggestion [here](https://github.com/aws/amazon-ecs-init/issues/344#issuecomment-671412255).

It currently looks like the ECS agent that comes with ECS Anywhere doesnt install the plugin needed to make use of `efsVolumeConfiguration`.

Start by reviewing the ECS Anywhere agent packaging and the amazon-ecs-volume plugin installation path described in the issue. Confirm how external instances handle efsVolumeConfiguration and define done as EFS mounts working without manual plugin installation; no files or tests are named.

Written by the indexing model from the issue text.