Added parameterless constructors in android typings - #6044

Related to: #6031

Currently in android typings we are generating classes accepting an implementation object for android interfaces. However if you want to create a class that implements an android interface you cannot just extend the generated android class as you'll need to supply the implementation in the super call. Here's an example:

class RunnableImpl extends java.lang.Runnable {
    constructor(private message: string) {
        super();
    }

    run() {
        console.log(this.message);
    }
}

var myRunable = new RunnableImpl("testing");

var handler = new android.os.Handler();
handler.postDelayed(myRunable, 5000);

In order this to be a valid typescript using the android typings we need to have a parameterless constructor in the java.lang.Runnable class.
So this PR adds such an empty constructor to each class generated from android interface.