Rename function parameter, if it named this

```typescript
export declare class SomeClass {
static foo(this: OtherClass, entity: T): any;
}
```
produce:
```kotlin
external open class SomeClass {
companion object {
fun foo(this: OtherClass, entity: T): Any = definedExternally
} // ^
} // Error: Parameter name expected
```
It could be `thisRef:`, for example

Start from the TypeScript declaration shown in the issue and trace how the converter names the generated Kotlin parameter for an explicit `this` parameter. Verify the generated declaration uses a valid parameter name such as `thisRef` and that the resulting Kotlin output compiles.

Written by the indexing model from the issue text.