chore: add additionalItems to OpenApi 3.0

[AlexVarchuk]

What/Why/How?

add addinionalItems to types for Openapi 3.0.
related to Redocly/redoc#2018

Reference

Testing

Screenshots (optional)

Check yourself

• Code is linted
• Tested with redoc/reference-docs/workflows
• All new/updated code is covered with tests

Security

• Security impact of change has been considered
• Code follows company security practices and guidelines

[github-actions]

Coverage report

Total coverage

Status	Category	Percentage	Covered / Total
🟡	Statements	65.91%	2639/4004
🔴	Branches	59.99%	1447/2412
🔴	Functions	57.85%	420/726
🟡	Lines	66.15%	2441/3690

Status of coverage: 🟢 - ok, 🟡 - slightly more than threshold, 🔴 - under the threshold

Show files with reduced coverage 🔻

Reduced coverage

Status	Filename	Statements	Branches	Functions	Lines
🟡	home/runner/work/redocly-cli/redocly-cli/packages/core/src/types/oas3.ts	71.43%	21.88% (+4.02% 🔼)	55.56% (+5.56% 🔼)	71.43%

Status of coverage: 🟢 - ok, 🟡 - slightly more than threshold, 🔴 - under the threshold

Report generated by 🧪jest coverage report action from a665227