[Android] One-finger drag rotates model, when initiated on the model

Currently, you can only rotate the model, when you initiate the rotation off model (i.e. on the background). But, when using a pen, dragging on top of the model with your finger does nothing.

**Suggestion:**
To improve the UX, dragging on top of the model with one finger should initiate the same action as dragging over the background (default: rotate).

**ArmorPaint version:**
Version 1.0 alpha

**OS / GPU model:**
Android 14
One UI 6.1.1

**Device:**
Samsung Tab S8

Reproduce the gesture on the Samsung Tab S8, then trace the one-finger drag handling that distinguishes starting on the model from starting on the background. Done means dragging one finger on the model performs the same default rotation as dragging on the background, while pen interaction remains usable.

Written by the indexing model from the issue text.