feat: clear state on SubscriptionsController, ClaimsController and ShieldController

[lwin-kyaw]

Explanation

Adds the state-clearing methods in three controllers:
SubscriptionController.clearSubscriptionState
ClaimsController.clearClaimsState
ShieldController.clearShieldState
Each test verifies that calling the clear method resets the controller state to its default values.

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

Low Risk
Low risk: adds new opt-in clearState helpers that reset controller state; behavior is unchanged unless consumers call the new methods.

Overview
Adds a new public clearState() method to ClaimsController, ShieldController, and SubscriptionController that resets each controller’s state to the corresponding getDefault*ControllerState().

Updates unit tests to validate that calling clearState() fully clears previously populated state, and records the new API in each package’s CHANGELOG.md.

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