[Metadata generator] Add default extend to java.lang.Object for class definitions that don't inherit #1922

Is your feature request related to a problem? Please describe.
In TS definitions, classes that don't inherit from other classes are missing the java.lang.Object inherited methods because the generator doesn't ensure they inherit from that class.

Describe the solution you'd like
Let class types that don't inherit from any class extend java.lang.Object.
e.g.

declare module org {
  export module maplibre {
    export module android {
      export module style {
        export module layers {
          export abstract class Layer extends java.lang.Object {
          }
        }
      }
    }
  }
}