Add NCISS decision points

[ahouseholder]

Creating this as a draft so we can figure out where to go with it.

Copilot Summary

This pull request introduces comprehensive support for National Cybersecurity Incident Scoring System (NCISS) decision points, including new data definitions, documentation, and navigation updates. It adds JSON schemas for various NCISS decision points (Functional Impact, Incident Severity, Information Impact, Observed Activity, Observed Activity Location, and Recoverability), provides corresponding documentation pages with usage examples, and updates the documentation navigation to include these new sections. Additionally, it introduces a new NcissDecisionPoint class in the codebase to model NCISS decision points.

NCISS Decision Point Data Definitions:

• Added JSON files defining NCISS decision points and their versions for:
  • Functional Impact (functional_impact_1_0_0.json, functional_impact_2_0_0.json) [1] [2]
  • Incident Severity (incident_severity_1_0_0.json, incident_severity_2_0_0.json) [1] [2]
  • Information Impact (information_impact_1_0_0.json, information_impact_2_0_0.json) [1] [2]
  • Observed Activity (observed_activity_0_0_1.json)
  • Observed Activity Location (observed_activity_location_1_0_0.json)
  • Recoverability (recoverability_1_0_0.json)

Documentation Additions:

• Created new documentation pages for each NCISS decision point, including code examples and versioning details:
  • Functional Impact
  • Incident Severity
  • Information Impact
  • Observed Activity
  • Observed Activity Location
  • Recoverability
• Added an index page introducing NCISS and listing all decision points

Documentation Navigation:

• Updated mkdocs.yml to add a new "NCISS Decision Points" section with links to all new documentation pages

Codebase Updates:

• Introduced the NcissDecisionPoint class in base.py to model NCISS decision points in the codebase