feat(error-check): add check for error message

[brendarearden]

Motivation and Context

When users are viewing public endpoints that reference internally marked schemas, we need a way to display an error message to let the user know they do not have permissions to view it.

InsertIssueNumberHere

https://github.com/stoplightio/platform-internal/issues/10534

Description

Added a check at the toplevelschemarow and at the schemarow levels to check for the x-sl-error-message property

How Has This Been Tested?

Manually tested changes by pulling this package into platform internal and manually making changes to the schema and schema permissions and seeing if the error message showed up as expected.

Added test coverage for SchemaRow

Screenshot(s)/recordings(s)

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• [ ] This PR's code follows as closely as possible the coding style/guidelines of this project.
• [ ] I have added error reporting and followed the error reporting guidelines.
• [ ] I have added event tracking and followed the event tracking guidelines.
• [ ] I have updated any relevant documentation accordingly to reflect this PR's changes.
• [ ] I have added automated tests (unit/integration/e2e/other) to cover my changes.
• [ ] All new and existing tests pass locally (excluding flaky CI tests).

[stoplight-bot]

:tada: This PR is included in version 4.6.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: