Add mouse to view magnifier command (#20238)
Closes #20127
Summary of the issue:
A command (script) to move the mouse cursor in the center of the magnified view was requested.
Description of user facing changes:
An unassigned command (script) to move the mouse cursor in the center of the magnified view has been added.
For now, the command remains unassigned, taking into account that many NVDA users won't use Magnifier at all and that too many magnifier key assignments for Magnifier may create many unused default gestures for them.
The command can operate even if a mouse button is active so that this command can be used for dragging actions.
Description of developer facing changes:
N/A
Description of development approach:
Factorise common code with the _keepMouseCentered method, and keep the specific part related to mouse button locking support separated.
