🛠️ [TASK] : Add API Endpoints to Catalyst Gateway Legacy endpoint

[bkioshn]

Summary

Add API Endpoints to Catalyst Gateway Legacy endpoint

Description

Add API Endpoints to Catalyst Gateway Legacy endpoint (No Implementation Needed)

• All endpoint should follow the OpenAPI schema in https://github.com/input-output-hk/catalyst-core/tree/f1553974f6bd531508107e1f973c734080b386e6/book/src/07_web_api/openapi

Endpoints

• POST /api/v0/search Schema Ref
• POST /api/v0/search_count Schema Ref
• GET /api/v0/challenges/ Schema Ref
• GET /api/v0/challenges/${id} Schema Ref
• GET /api/v0/node/stats Schema Ref
• GET /api/v0/account/{account_id} Schema Ref