FINERACT-2501: Collaborative API Standardization - Savings Module

[Ambika-Sony]

…## Description
This PR is part of the collaboration with Edward Kang (@edk12564) on FINERACT-2501.

Changes:

• Standardized operationIds in SavingsAccountsApiResource.java to follow the methodName + Entity + Description convention.
• Restored logic in the Savings module that was accidentally deleted during a previous conflict resolution.
• Updated SavingsAccountsExternalIdTest.java to match new operation names.

Note on Build:

The local build is currently failing due to dependency issues in the Teller/Cashier module (outside the scope of my Savings work). I am opening this PR to sync my changes before my university exams. I will resolve the merge conflicts and build errors once I return in a few days.

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[adamsaghy]

@Ambika-Sony Please rebase.