Implement draft-ietf-ppm-dap-17+

[tgeoghegan]

There's at least two DAP versions beyond draft-ietf-ppm-dap-16 (whose implementation is tracked here). Draft 17 has been published and draft 18 is underway. This issue tracks implementing what will become draft-ietf-ppm-dap-18.

I diffed tag draft-ietf-ppm-dap-16 against main + the three outstanding PRs on the doc (ietf-wg-ppm/draft-ietf-ppm-dap#774, ietf-wg-ppm/draft-ietf-ppm-dap#775, ietf-wg-ppm/draft-ietf-ppm-dap#776) and that indicates we have the following changes to make:

• update to a libprio that implements draft-irtf-cfrg-vdaf-18 (Release prio 0.18 for draft-irtf-cfrg-vdaf-18 libprio-rs#1391)
• update domain separation tags. Let's jump ahead to "dap-18".
• use singular media types (e.g. application/dap-hpke-config-list -> application/ppm-dap;message=hpke-config-list) (draft-ietf-ppm-dap-18 HTTP media types #4424)
• VDAF "preparation" is renamed "verification"
  • this will make a huge diff!
• TimePrecision is now defined in DAP, not taskprov (Move TimePrecision out of taskprov module #4368)
• DAP now defines TaskConfiguration and VDAF config encodings, replacing TaskConfig and VdafConfig from taskprov
  • TaskConfiguration has extensions
• Instead of task_start and task_duration in TaskConfiguration, we have a TaskInterval extension
• TaskConfiguration gets included in HPKE AADs
  • InputShareAad
  • AggregateShareAad
• collection job extensions
• AggregationJobInitReq now includes verification key ID field
• UploadResponse renamed UploadErrors
• Extensions (task, collection, upload) MUST appear in strictly increasing order
• Update protocol version in aggregator-api config response to "DAP-18"