[Enhancement] Consolidate OECD Interest Rate Endpoints as a Single Function

[deeleeramone]

1. Why?:

   • Unnecessary endpoints existing where the only difference is one parameter.

2. What?:

   • Deprecates:
     • obb.economy.immediate_interest_rate
     • obb.economy.long_term_interest_rate
     • obb.economy.short_term_interest_rate
   • Adds:
     • obb.economy.country_interest_rates

3. Impact:

   • Removes redundant code and improves organization of endpoints.

4. Testing Done:

   • Integration/Unit
   • CLI

[jmaslek]

thoughts on just calling it interest_rates instead of country_interest_rates

[deeleeramone]

thoughts on just calling it interest_rates instead of country_interest_rates

not opposed.

[IgorWounds]

LGTM! I'd add the change @jmaslek proposed @deeleeramone.

[deeleeramone]

LGTM! I'd add the change @jmaslek proposed @deeleeramone.

If no objections, I'll keep the model name as 'CountryInterestRates' so not to create confusion with something that may belong with Fixed Income.