FINERACT-2652: Decouple SavingsAccount from injected collaborators

[alberto-art3ch]

Description

We are removing @transient service fields from SavingsAccount.

The transient SavingsAccountTransactionSummaryWrapper, SavingsHelper and ConfigurationDomainService (previously injected post-hydration via setHelpers) and the accountNumberRequiresAutoGeneration flag are removed. The three stateless collaborators are bundled into a new singleton SavingsContext bean that is passed as a method parameter; the account-number flag is derived at the service layer.

FINERACT-2652

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