Refactor CI to use the OSCAL CLI

[Rene2mt]

This is a ...

improvement - something could be better

This relates to ...

• the FedRAMP OSCAL Registry
• the FedRAMP OSCAL baselines
• the Guide to OSCAL-based FedRAMP Content
• the Guide to OSCAL-based FedRAMP System Security Plans (SSP)
• the Guide to OSCAL-based FedRAMP Security Assessment Plans (SAP)
• the Guide to OSCAL-based FedRAMP Security Assessment Results (SAR)
• the Guide to OSCAL-based FedRAMP Plan of Action and Milestones (POA&M)
• the FedRAMP SSP OSCAL Template (JSON or XML Format)
• the FedRAMP SAP OSCAL Template (JSON or XML Format)
• the FedRAMP SAR OSCAL Template (JSON or XML Format)
• the FedRAMP POA&M OSCAL Template (JSON or XML Format)

User Story

As a developer, I want the FedRAMP automation repository to be refactored and simplified so that it uses a single tool (OSCAL CLI) for OSCAL content validation, content conversion, and profile resolution.

Goals

• Single tool (OSCAL CLI) to validate XML, JSON, and YAML OSCAL files
• Use Makefiles to simplify build process and make it easier to debug CI/CD locally / on dev systems
• Speed up build performance

Dependencies

No response

Acceptance Criteria

• All FedRAMP Documents Related to OSCAL Adoption (https://github.com/GSA/fedramp-automation) affected by the changes in this issue have been updated.
• A Pull Request (PR) is submitted that fully addresses the goals of this User Story. This issue is referenced in the PR.

Other information

No response

[Rene2mt]

The updated CI should:

• 1) better support incremental builds. Currently, the content generation pipeline rebuilds all content, even if it doesn't change.

• 2) remove the old validation tool website build.

• 3) figure out a better dependency management approach using dependabot.

• 4) provide a means to integrate the content validation test suite we plan to build.