fix: validate configurable rules severity overrides correctly in config

[tatomyr]

What/Why/How?

Resolved an issue where overrides for the severity of configurable rules raised warnings when validating the config.

Reference

Closes #1865

It's a follow-up to #1811

Testing

Screenshots (optional)

Check yourself

• Code changed? - Tested with redoc/reference-docs/workflows (internal)
• All new/updated code is covered with tests
• New package installed? - Tested in different environments (browser/node)

Security

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

[changeset-bot]

🦋 Changeset detected

Latest commit: f52ec01

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@redocly/openapi-core	Patch
@redocly/cli	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
redocly lint packages/core/src/benchmark/benches/rebilly.yaml	965.6 ± 14.2	948.3	985.1	1.00
redocly-next lint packages/core/src/benchmark/benches/rebilly.yaml	966.9 ± 17.3	946.5	998.5	1.00 ± 0.02

[github-actions]

Coverage report

St.❔	Category	Percentage	Covered / Total
🟡	Statements	78.6%	5053/6429
🟡	Branches	67.18%	2059/3065
🟡	Functions	73.16%	834/1140
🟡	Lines	78.88%	4767/6043

Show files with reduced coverage 🔻

St.❔	File	Statements	Branches	Functions	Lines
🟢	... / redocly-yaml.ts	81.54% (-1.79% 🔻)	47.37% (-2.63% 🔻)	71.43%	81.1% (-1.82% 🔻)

Test suite run success

835 tests passing in 120 suites.

Report generated by 🧪jest coverage report action from f52ec01