[FR] x-elbv2.MacroParameters x-s3 logging

[JohnPreston]

As a elbv2 user, I'd like to get the LB logs shipped into AWS S3.
Given that with ECS Comose-X I can create both things, with x-elbv2 and x-s3, I'd like to be able to define a one-liner that will auto-configure logging from ELB to S3 automatically

x-s3:
  logging-bucket: {}

x-elbv2:
  publicLB:
    MacroParameters:
      S3Logging: x-s3::logging-bucket