perf(multichain-account-service): add Solana account batching

[ccharly]

Explanation

Implementing proper batching for our Solana account provider.

References

• perf(multichain-account-service): add :createMultichainAccountGroups action to batch account creation  #7801
• perf(account-tree-controller): use batched account creation in backup & sync #7907

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

Medium Risk
Changes core Snap-based account creation paths for Solana/Bitcoin/Tron, including new batching behavior and a new createAccounts call into the Snap keyring; bugs here could create wrong accounts or impact discovery/alignment flows.

Overview
Adds an optional batched account-creation path for Snap-based providers (Solana/Bitcoin/Tron). Providers now support a createAccounts.v2 config flag that switches createAccounts (single and range) from repeated createAccount calls to a single SnapKeyring.createAccounts call, while keeping v1 behavior as the default.

Refactors provider internals and tests to cover v1 vs v2 behavior. SnapAccountProvider’s restricted keyring interface now exposes createAccounts, discovery flows route through the unified creation helper, and unit tests add mocks plus assertions for idempotency, range handling, and timeout behavior under both versions; changelog is updated to note Solana range batching.

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Near-identical #createAccounts duplicated across BTC and TRX providers

Low Severity

BtcAccountProvider.#createAccounts and TrxAccountProvider.#createAccounts are ~70-line methods that are structurally identical — the only differences are addressType (BtcAccountType.P2wpkh vs TrxAccountType.Eoa) and scope (BtcScope.Mainnet vs TrxScope.Mainnet). This PR expanded the prior ~10-line duplication to ~70 lines each by adding the v1/v2 branching logic. This substantially increases the maintenance burden and the risk that a future bug fix is applied to one but not the other.

Additional Locations (1)

• packages/multichain-account-service/src/providers/BtcAccountProvider.ts#L80-L155