Get publicly referable APIs for Devant backend

Devant backend APIs currently exist internally(https://github.com/wso2-enterprise/choreo-system-apis/tree/prod/cp) but aren’t exposed publicly due to inconsistent change management.

This issue tracks aligning Devant’s backend API needs with the WSO2 Cloud API redesign effort, so that all APIs Devant uses are properly versioned, documented, and publicly referable.