[Story] Implement Application Service API

https://spec.matrix.org/v1.6/application-service-api/

Based on user case described here https://www.notion.so/linagora/Automatic-channels-89ba6f97bc90474ca482a28cf3228d3e

Related issues:

• Transaction endpoint : #44 (closed)
• Queries endpoinst: #52 (closed)