Style the Magnification Window - Window Mode

Modifying the design of the magnification window in window mode:
1. We change the window to rounded rectangle with styled border.
2. We change the design of the window border when it is in "Edit"
   state.
3. We change the design of the drag handle to a solid shape.

Bug: 257272333
Test: manual - attach videos with the bug
Change-Id: I69310ae7db04cee116021ad951082362efc95fad