Update various Windows category routines to avoid deprecated warnings

[delphidabbler]

In Delphi 12, and possibly some earlier Delphi versions back to Delphi 10.1, compiling HScrollbarHeight and VScrollbarWidth results in a deprecated warning due to calls to StdCtrls.ssVertical etc. (from StdCtrls.TScrollStyle). Need to use values from the System.UITypes.TScrollStyle enumeration instead.

WinControlScrollbars and WindowScrollbars have similar warnings concerning deprecation of StdCtrls.TScrollStyle.