feat: add PoC of handling discriminator for allOf case in OpenAPI 3.1

[glowcloud]

Notes on the idea of handling allOf discriminator:

Dereference: dereferenced value of SchemaElement should be stored within allOfDiscriminatorMapping if

1. SchemaElement is an item of AllOfElement
2. SchemaElement has a schemaName metadata
3. parent SchemaElement has a schemaName metadata

# schemas
components:
  schemas:
    Pet:
      properties:
        petType:
          type: string
     discriminator:
       propertyName: petType
    Cat:
      allOf:
        - $ref: '#/components/schemas/Pet' # => SchemaElement Cat should be mapped to Pet

# allOfDiscriminatorMapping
Pet: [ 
  # dereferenced SchemaElement Cat
  allOf:
    - properties:
         petType:
           type: string
       discriminator:
         propertyName: petType
 ]

Normalization: should be similar to oneOf/anyOf discriminator normalization but this time we will be creating the normalized mapping based on the items of allOfDiscriminatorMapping instead of items of oneOf/anyOf fields. External references and references not pointing to internal components/schemas/<schemaName> are also not being handled here.

[robert-hebel-sb]

adding types for visit options argument would fix that error

[robert-hebel-sb]

It seems there are many issues within typings. If resolving all TS errors exceeds the scope of the task, we can handle it in a separate ticket

[glowcloud]

It seems there are many issues within typings. If resolving all TS errors exceeds the scope of the task, we can handle it in a separate ticket

Let's handle it separately - we have many similar cases with the typings, we could try addressing them as well.