[ENG-3815] feat(microsoft): Webhook Message format

[Cobalt0s]

Description

Implements Microsoft subscription events and refactors HubSpot event tests to use testroutines.SubscriptionEventTestCase. It is used as a template for all future unit tests of this kind.

Key changes

• Reusable test routine
  SubscriptionEventTestCase accepts a generic common.Event and validates it by casting to:

  • common.CollapsedSubscriptionEvent (for list-based events)
  • common.SubscriptionEvent (core contract assertions)
  • common.SubscriptionUpdateEvent (adds updated-fields validation)

  Test inputs use a unified parameter structure, enabling universal validation across all event interfaces.

• Microsoft event implementation
  Implements the event interfaces for Microsoft subscription events.
  Responses always contain a single item, but are still modeled as a common.CollapsedSubscriptionEvent.

• Exported event collection
  webhook.EventCollection is exported as microsoft.EventCollection for external server use.

NOTE: the clientState is used to carry the objectName. Microsoft returns the resource name but that would require mapping each and every string back to the object name we use for Read/Write, etc.

[linear]

ENG-3815 Microsoft subscribe actions

[Cobalt0s]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• [ENG-3815] feat(microsoft): Impl Subscription Maintainer #2946
• [ENG-3815] feat(microsoft): Impl Update Subscription #2879
• [ENG-3815] feat(microsoft): Impl Delete Subscription #2880
• [ENG-3815] feat(microsoft): Impl Create Subscription #2878
• feat(subscriptions): Scripts for consuming events #2948
• [ENG-3815] feat(microsoft): WebhookVerifier #2877
• [ENG-3815] feat(microsoft): Webhook Message format #2875 👈 (View in Graphite)
• [ENG-3815] feat(microsoft): BatchRecordReader #2874
• feat(microsoft): Batch API #2945
• feat(components): Subscription interfaces #2876
• feat(codec): Dual marshal preserve RawJSON #2276 : 1 other dependent PR (#2277 )
• tidy(testutils): Relocate CompareResult #2944
• main

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