Issue #21978/#21979: Fixed issue with inputs not saving value when moving through grid rows

- In the existing keyDown function in XV.Input, added a check so that if the user is using the arrow keys the value will save in the widget before moving to the next row (in the case of the grid) (#21979)
- This also appears to fix the issue with the Item widget (#21978)
- Removed unnecessary keyDown functions in child kinds, or changed them to inherit from the parent kind keyDown
- Commented out a Firefox fix in the Date widget that was causing all years before 2000 to be converted into the 2000s (separate bug to fix Firefox 2-digit date issue).