Multi-port TCP app access

[ravicious]

RFD

Tasks

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1. Add Ports field to app spec #47706
   backport/branch/v17 documentation no-changelog size/lg +4
2. Add TargetPort to RouteToApp & use it to route connections to multi-port TCP apps #49047
   application-access backport/branch/v17 no-changelog size/md +4
3. Pass port from VNet to local proxy #49453
   backport/branch/v17 no-changelog size/md +3
4. Surface target ports in tsh and Connect #49688
   backport/branch/v17 no-changelog size/md tsh ui +5
5. VNet: Refuse conn if local port doesn't match app spec #49944
   application-access backport/branch/v17 no-changelog size/md tsh ui +6
6. ConvertAuditEvent: Set SessionStartEvent.App.IsMultiPort #50008
   no-changelog size/sm +2
7. Add docs for multi-port TCP access #50216
   backport/branch/v17 documentation no-changelog size/sm +4

The tasks above allow the design partner to evaluate multi-port TCP app access by using it through VNet. We want to ship those changes first and then do some follow-up tasks.

Follow-ups

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1. tsh proxy app: Add support for multi-port TCP apps #50429
   backport/branch/v17 size/md tsh +3
2. Add multi-port support to local proxies in Connect