Entity Role requires addition for System of Interest concept

[Chris-Turner-NIST]

Reasoning:
Currently, Entity Role's purpose is for defining relevant security boundaries across existing assessment systems. This change will enable tracking of these boundaries using the concept of System of Interest. (Used by CVSS v4.0 and SSVC 2.0)

CVSS v4.0 will release towards the end of 2023 (slated for 10/31/23 at the moment).
SSVC v2.0 has been released since 2020

Areas to enhance:

• Data Model - Entity Role
  website/content/specification/values/entity-role.md

ADD
System of Interest: See CVSS v4.0 Section ?? for a full explanation of System of Interest

• Vulnerable: Associated Context is considered to contain the vulnerability.

• Subsequent: Associated Context is where impacts of the vulnerability are realized. The Subsequent System may or may not be the Vulnerable System.

• JSON Schema
  

  vulntology/schema/vulntology-json-schema-1.0-draft.json

  Lines 200 to 208 in a0dd316

  	"EntityRole": {
  	"type": "string",
  	"enum": [
  	"Security Authority::Primary",
  	"Security Authority::Secondary",
  	"Component::Vulnerable",
  	"Component::Impacted"
  	]
  	},

ADD

                "System of Interest::Vulnerable",
                "System of Interest::Subsequent",

• Overall Graph
  https://github.com/usnistgov/vulntology/blob/a0dd31603661d966c91c2db86b5d64bc629115b5/website/static/figures/vulntology-graph.png

• Graph Snippets

• https://github.com/usnistgov/vulntology/blob/a0dd31603661d966c91c2db86b5d64bc629115b5/website/static/figures/graphsnippets/EntityRoleSnippet.png

• https://github.com/usnistgov/vulntology/blob/a0dd31603661d966c91c2db86b5d64bc629115b5/website/static/figures/graphsnippets/ActionSnippet.png

• https://github.com/usnistgov/vulntology/blob/a0dd31603661d966c91c2db86b5d64bc629115b5/website/static/figures/graphsnippets/ContextSnippet.png

• https://github.com/usnistgov/vulntology/blob/a0dd31603661d966c91c2db86b5d64bc629115b5/website/static/figures/graphsnippets/ImpactMethodSnippet.png

• https://github.com/usnistgov/vulntology/blob/a0dd31603661d966c91c2db86b5d64bc629115b5/website/static/figures/graphsnippets/VulnerabilitySnippet.png