[CL-725] dialog adjustments (#15660)

* update dialog spacing/borders

* update scroll bottom threshold

* add shadow to dialog

* adjust simple dialog shadow

* update scroll util comment

* add background input to other dialog stories

* assign initial value to isScrollable

* add larger padding on alt background content

* update tab border color

* update tab content padding

* update tab content spacing

* revert tab border color change

* bring back tab border color changes

* update web header border to match new tab border

* add background to props in story

libs/components/src/utils/has-scrolled-from.ts

@@ -26,7 +26,8 @@ export const hasScrolledFrom = (scrollable?: Signal<CdkScrollable>): Signal<Scro
         startWith(null),
         map(() => ({
           top: _scrollable.measureScrollOffset("top") > 0,
-          bottom: _scrollable.measureScrollOffset("bottom") > 0,
+          // Using 1 as the threshold here because `_scrollable.measureScrollOffset("bottom")` returns '0.5' at the bottom most position in Chrome
+          bottom: _scrollable.measureScrollOffset("bottom") > 1,
         })),
       ),
     ),