fix: $anchors in openapi documents are not properly parsed

[tatomyr]

What/Why/How?

Closes https://github.com/Redocly/redocly-cli/issues/462

In order to not fail when bundling, $anchors need to be resolved correctly. I decided to collect all $anchors into anchorRefsMap while walking a document.

Reference

JSON Schema documentation on $anchor More on $anchor

Testing

Screenshots (optional)

Check yourself

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

Security

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

[github-actions[bot]]

Coverage report

St.:grey_question:	Category	Percentage	Covered / Total
🟡	Statements	73.54%	3324/4520
🟡	Branches	64.93%	1866/2874
🟡	Functions	66.08%	563/852
🟡	Lines	73.55%	3089/4200

Test suite run success

510 tests passing in 84 suites.

Report generated by 🧪jest coverage report action from 35108a9ae11aef26ee9f9f2f6f2a88164bcb296d