FINERACT-2675: Fix template endpoint

[AnvayKharb]

Description

This PR fixes FINERACT-2675 by restoring the template endpoint responses expected by the Mifos Web App.

Problem

After recent backend changes, the Templates API response contract changed:

• GET /templates returned only template IDs, causing the Name, Entity, and Type columns to appear blank.
• GET /templates/{id}/template returned a raw template object instead of the wrapper containing template, entities, and types, causing the Edit Template page to fail.

Changes

• Restore full template data for GET /templates.
• Restore the response wrapper for GET /templates/{id}/template containing:
  • template
  • entities
  • types
• Preserve the existing behavior of GET /templates/{id}.
• Return template entity and type values in the format expected by the Web App.
• Add regression tests covering:
  • Template list response
  • Template edit response
  • Template retrieval
  • Entity/type mapping
  • Query filtering

Testing

Verified by:

• Running the relevant unit tests.
• Running Spotless checks.
• Confirming the restored API response matches the expected Web App contract.

Fixes FINERACT-2675.