[kotlin] better oneOf, anyOf support (#18382)

* add validteJsonElement

* add oneOf support

* various fixes, add tests

* minor fixes

* minor fixes

* update data class

* remove comments

* array support, add test

* update api client constructor

* add anyOf support

* add new files

* fix merge

* update

* update

* update

* update

samples/client/petstore/kotlin-uppercase-enum/README.md

@@ -43,9 +43,9 @@ This runs all tests and packages the library.
 
 All URIs are relative to *http://petstore.swagger.io/v2*
 
-Class | Method | HTTP request | Description
------------- | ------------- | ------------- | -------------
-*EnumApi* | [**getEnum**](docs/EnumApi.md#getenum) | **GET** /enum | Get enums
+| Class | Method | HTTP request | Description |
+| ------------ | ------------- | ------------- | ------------- |
+| *EnumApi* | [**getEnum**](docs/EnumApi.md#getenum) | **GET** /enum | Get enums |
 
 
 <a id="documentation-for-models"></a>

samples/client/petstore/kotlin-uppercase-enum/docs/EnumApi.md

@@ -2,9 +2,9 @@
 
 All URIs are relative to *http://petstore.swagger.io/v2*
 
-Method | HTTP request | Description
-------------- | ------------- | -------------
-[**getEnum**](EnumApi.md#getEnum) | **GET** /enum | Get enums
+| Method | HTTP request | Description |
+| ------------- | ------------- | ------------- |
+| [**getEnum**](EnumApi.md#getEnum) | **GET** /enum | Get enums |
 
 
 <a id="getEnum"></a>