oas3-valid-...-example: Only checks example, but not examples

[m-mohr]

Describe the bug

This is somewhat related to #882: All the oas-valid-...-example rules only check the examples in example, but not the examples in examples.*.value.

To Reproduce

OAS3 file adapted from the second test in src/rulesets/tests/templates/_oas-examples.ts:

    {
      openapi: '3.0.0',
      headers: {
        xoxo: {
          schema: {
            type: 'string',
          },
          examples: {
            test1: {
              value: 123
            },
          },
        },
      },
    }

If I add to the test:

  test('will fail when simple example is invalid (examples)', async () => {
    const results = await s.run({
      openapi: '3.0.0',
      [path]: {
        xoxo: {
          schema: {
            type: 'string',
          },
          examples: {
            test1: {
              value: 123
            },
          },
        },
      },
    });
    expect(results).toEqual([
      expect.objectContaining({
        severity: DiagnosticSeverity.Error,
        code: ruleName,
        message: '`examples.*.value` property type should be string',
      }),
    ]);
  });

and run: npm test "oas3-valid-oas-header", it doesn't check the examples.test.value value.

Expected behavior

All examples should be checked.

Environment (remove any that are not applicable):

• Library version: 5.0.0
• OS: Windows 10