feat(efs): One-Zone filesystem

[badmintoncryer]

In this PR, I have added support for creating one zone filesystems.

As discussed in the issue, I considered including availabilityZoneName in the props, but for now, I have added only the oneZone argument.

The efs.FileSystem construct also generates a mount target simultaneously. However, when creating a one zone file system, both the mount target and the file system should be located in the same Availability Zone. The issue arises because the name of the Availability Zone where the mount target will be placed (obtained from props.vpc.selectSubnets()) remains token, making it impossible to compare it with the given availabilityZoneName.

Please let me know if there is a smart way to resolve this.

Closes #15864

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[lpizzinidev]

Thanks 👍
I left some comments for minor documentation adjustments and a question.

[lpizzinidev]

Not sure about this, what happens if the user specifies subnets from different AZs?

[badmintoncryer]

Probably, the return value from props.vpc.selectSubnets(subnetSelection) is an empty array, and the mountTarget is not created.

Should it be considered an error when the return value of selectSubnets is an empty array with oneZone=true?

[lpizzinidev]

Given:

• Amazon EFS One Zone file systems support only a single mount target which is located in the same Availability Zone as the file system. You cannot add additional mount targets.
• selectSubnets Requires that at least one subnet is matched, throws a descriptive error message otherwise.

I think that the best option here is to validate that the users can specify either oneZone or vpcSubnets, not both, to prevent deployment errors and change the implementation accordingly.

[badmintoncryer]

@lpizzinidev Thank you for your review!! I have addressed the comments you provided.

[badmintoncryer]

@lpizzinidev I have implemented an error for cases where the vpcSubnets argument is specified in a oneZone file system.

[lpizzinidev]

Thanks, just a minor change on the validation message.

[badmintoncryer]

@lpizzinidev Thanks. I fixed it!

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[paulhcsun]

Thanks for adding this support for One-Zone filesystems @badmintoncryer! And thanks for reviewing @lpizzinidev!

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