Reduce object allocations in AudioListener

[capdevon]

Reduce object allocations when ALAudioRenderer update listener each time the Camera is moved:

This pull request refactors the Listener class in the jMonkeyEngine audio system. The main changes include initializing the location, velocity, and rotation fields at declaration instead of in the constructor, removing redundant constructor assignments, and introducing reusable Vector3f instances (left, up, direction) for direction calculations.

Methods that return direction vectors now store results in these fields rather than creating new objects, improving memory efficiency and reducing unnecessary allocations. Overall, the changes streamline object management and optimize performance in the Listener class.

https://github.com/jMonkeyEngine/jmonkeyengine/blob/master/jme3-core/src/main/java/com/jme3/audio/openal/ALAudioRenderer.java#L768

    private void applyListenerRotation(Listener listener) {
        Vector3f dir = listener.getDirection(); // <--
        Vector3f up = listener.getUp(); // <--
        // Use the shared FloatBuffer fb
        fb.rewind();
        fb.put(dir.x).put(dir.y).put(dir.z);
        fb.put(up.x).put(up.y).put(up.z);
        fb.flip();
        al.alListener(AL_ORIENTATION, fb);
    }

[riccardobl]

I've reverted the changes to the existing getters. Since the listener isn't only an internal API, changing their behavior could break existing code, and because the defect isn't severe, it isn't worth risking hard-to-debug regressions for developers, imo.

Instead, I added new getters that populate the passed store object (a pattern used frequently elsewhere in jME), and updated the Audio Renderer to use these new getters.

I think this is a good resolution.

[capdevon]

Refactor Listener.getLeft(), Listener.getUp(), and Listener.getDirection() to rely on Quaternion.getRotationColumn(int, Vector3f), which already handles null store vectors.
This removes redundant null checks and eliminates duplicated code.