Issue-143: Add Mercury Injection content endpoints

Type of change

• Bug Fix
• Feature

Does this introduce a change in the core logic?

• [No]

Does this introduce a change in the cloud provider implementation, and if so which cloud?

• AWS
• Azure
• GCP
• IBM

Does this introduce a change that must be documented in the README.md file?

• [No]

Updates description?

Add Mercury Injection content endpoints, schema, model, and tests. Closes #143 (closed).