Fix manual entry not working in Financial Connections

[torrance-stripe]

Summary

• Switch the openFinancialConnections bridge in EmbeddedComponent from collectFinancialConnectionsAccounts to collectBankAccountToken, mirroring what the native iOS and Android Connect SDKs already do. This fixes manual bank-account entry in ConnectAccountOnboarding — previously, manual entry didn't return a token, so no external account was created on the connected account.
• Add a toStripeJsBankAccountToken mapper that converts the RN SDK's camelCase BankAccountToken to the snake_case Stripe.js API shape (token.bank_account.currency, etc.) that connect-js/ARK expects.
• Add connectedAccountId to CollectBankAccountTokenParams so the bridge call type-checks (the native layers already read this field).

Motivation

User reported a bug

Testing

• I tested this manually
• I added automated tests

• Reproduced the issue locally, i.e. that manual entry didn't work on livemode
• Afterwards, tested that manual entry + standard FC flow worked

Documentation

Select one:

• I have added relevant documentation for my changes.
• This PR does not result in any developer-facing changes.

[maragues-stripe]

LGTM!