feat: subscription cancel type and request param

[tuna1207]

Explanation

Subscription controller add cancel type to subscription data and cancel immediate params in cancel subscription request

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
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Introduces cancellation semantics and request support across controller, service, and types.

• Adds CANCEL_TYPES and CancelType; Subscription.cancelType is now part of state
• New CancelSubscriptionRequest (with optional cancelAtPeriodEnd) used by SubscriptionController.cancelSubscription and SubscriptionService.cancelSubscription
• Service now POSTs { cancelAtPeriodEnd } to subscriptions/:id/cancel
• Updated exports in index.ts to expose CancelType, CancelSubscriptionRequest, and CANCEL_TYPES
• Tests adjusted to include cancelType and new cancel request shape; changelog updated

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

[tuna1207]

@metamaskbot publish-preview