The functionality of snap with constraints relies on the position of
the transformed object.
Previously, snap to grid with constraints was restricted to the Move
operation.
Consequently, the 'Set Snap Base' mode, as well as other transformation
modes, failed to compute the moved position.
As a result, it lacked support for snap to grid with constraints and
would even crash under such circumstances.
The solution involves eliminating the reliance on the Move operator and
instead calculating the position based on mouse position.
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