feat: subscription sponsorship intents

[lwin-kyaw]

Explanation

Added new method, submitSponsorshipIntents, which submits the user's sponsorship intents for new subscription with crypto.

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed, highlighting breaking changes as necessary
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes

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Note

Introduces submitSponsorshipIntents across types, service, and controller to POST sponsorship intents for crypto subscriptions, plus optional isSponsored flag and test/exports updates.

• API additions
  • types.ts: Add SubmitSponsorshipIntentsRequest and optional isSponsored to StartCryptoSubscriptionRequest.
  • SubscriptionService: New submitSponsorshipIntents(request) POSTs to transaction-sponsorship/intents.
  • ISubscriptionService: Declare submitSponsorshipIntents.
• Controller
  • SubscriptionController: Add public submitSponsorshipIntents(request) with user-not-subscribed check; register new messenger action ${controllerName}:submitSponsorshipIntents.
• Exports
  • index.ts: Export SubmitSponsorshipIntentsRequest (and related plumbing).
• Tests
  • Add unit tests for service and controller submitSponsorshipIntents (success, already subscribed, and error cases).
• Docs/Changelog
  • Update CHANGELOG with new method.

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[lwin-kyaw]

@metamaskbot publish-preview