Issue title: Upgrade Cromwell Pipelines API Backend to version 2. 
 Issue body: Please upgrade Cromwell Pipelines API Backend to version 2. This will be necessary for our portal to launch workflows against GCS "requester pays" buckets with appropriate billing
 Comments: 
 Comment 0: This can't be closed yet, the previous PR was ground work for this but was not effectively adding V2 support
 Comment 1: @gemmalam, does this mean "requester pays" buckets can now be used with cromwell?
 Comment 2: @nrockweiler hello, please refer to https://github.com/broadinstitute/cromwell/issues/2916 for requester pays updates.
 Comment 3: thanks
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