[FEATURE] Achieve Kotlin feature parity for code generation

### Why do we need this improvement?

The Java code generation is very complete; API classes have well-defined hierarchies (enabling API polymorphism) and Jackson annotations (when enabled). The generated Kotlin code is missing most of these capabilities. Code generated for JVM languages should have functional parity

### How will this change help?

Adding feature parity will mean that teams working in Kotlin will be able to exclusively work with Kotlin code, syntax, and paradigms.

### Screenshots

_No response_

### How could it be implemented/designed?

Leverage the existing Java generation logic and port the class hierarchy generation and Jackson integration to the Kotlin-specific generators

### 🚧 Breaking changes

No

### 👀 Have you checked for similar open issues?

- [x] I checked and didn't find a similar issue

### 🏢 Have you read the Contributing Guidelines?

- [x] I have read the [Contributing Guidelines](https://github.com/asyncapi/.github/blob/master/CONTRIBUTING.md)

### Are you willing to work on this issue?

None

Start by comparing the existing Java generation logic with the Kotlin-specific generators. Trace how API class hierarchies and Jackson integration are produced in Java, then identify the corresponding Kotlin generation paths. Done means generated Kotlin supports the requested hierarchy and Jackson capabilities with functional parity.

Written by the indexing model from the issue text.