perf(solana-wallet-snap): resolve Core token accounts lazily

[ulissesferreira]

Summary

• Avoid resolving SPL associated token account pubkeys while reading Core-backed balances and asset lists.
• Resolve the ATA only when transaction history needs getSignaturesForAddress.
• Preserve the existing Snap path by using the RPC-provided pubkey without fetching mint data.
• Start account lookup, metadata lookup, saved transaction lookup, ATA resolution, and local history lookup in parallel where independent.

Validation

• ENVIRONMENT=test yarn workspace @metamask/solana-wallet-snap exec jest --runInBand src/core/services/assets/adapters/CoreAssetsAdapter.test.ts src/core/services/assets/utils/mapControllerAsset.test.ts src/core/services/transactions/TransactionsService.test.ts
• 3 suites passed, 28 tests passed

This PR targets the branch backing #122.

[ulissesferreira]

These changes will have to be done against main for reviewability so this will be superseded by #245. In there we first start by implementing that change independent of using AssetsController for storage or not.