test(express): added supertest for wallet recover token

[lokesh-bitgo]

Ticket: WP-6330

[Copilot]

Pull Request Overview

Adds a comprehensive supertest + sinon-based test suite for the walletRecoverToken typed route, covering success paths, error handling, invalid inputs, and edge-case response validation.

• Introduces end-to-end style tests hitting /api/v2/:coin/wallet/:id/recovertoken with varied payloads
• Mocks BitGo coin and wallet interactions using sinon to simulate diverse success and failure scenarios
• Expands response validation via RecoverTokenResponse codec, including malformed and type-mismatch cases

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