Fix lost skip configurations in allof blocks and readOnly and writeOnly in examples

[NickUfer]

What/Why/How?

The sampler ignores readOnly and writeOnly on properties in allOf's and in examples.

The problem with allOf's is that the readOnly and writeOnly information of properties is lost in them. This PR preserves the information by marking the properties with a special object MARKED_FOR_REMOVAL which were supposed to be removed by skipNonRequired=true, skipReadOnly=true or skipWriteOnly=true. Before the result is returned all values which are supposed to be removed are removed.

The problem with having example values in the sample even if they are readOnly or writeOnly is fixed by traversing the schema again for which the example is intended and removing all values which are invalid from the example.

Reference

Fixes #140 Fixes https://github.com/Redocly/redoc/issues/1238

Testing

Tests for the changes were added.

Screenshots (optional)

Check yourself

• [X] Code is linted
• [X] Tested
• [X] All new/updated code is covered with tests

Security

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

[NickUfer]

Simplification is IMO not possible because the architecture of the sampler project is flawed. Crucial information about properties is lost in the process and IMO a rewrite is necessary to fix this, which includes keeping as much information as possible until the final merging of a single object. That's why I decided to write this fix, even if it is not exactly the perfect solution.

About the additionalProperties, yes that is a problem. Maybe the example filtration should be disabled by default and only enabled when the schema includes additionalProperties: false