FINERACT-2491: Refactor SavingsEnumerations to use switch expression

[Abdelrahman-358]

Description

Describe the changes made and why they were made. (Ignore if these details are present on the associated Apache Fineract JIRA ticket.)

Checklist

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[IOhacker]

Could you please add some test classes?

[Abdelrahman-358]

Could you please add some test classes?

Sure, I'll add the tests.