fix(popover): Use absolute position and strategy (#1666)

This fix minimizes the amount of jitter when an
open popover tries to reposition against its
target while scrolling or resizing.

Author: rkaraivanov

src/components/popover/popover.ts

@@ -276,7 +276,7 @@ export default class IgcPopoverComponent extends LitElement {
       {
         placement: this.placement ?? 'bottom-start',
         middleware: this._createMiddleware(),
-        strategy: 'fixed',
+        strategy: 'absolute',
       }
     );
 

src/components/popover/themes/light/popover.base.scss

@@ -6,7 +6,7 @@
 }
 
 :popover-open {
-    position: fixed;
+    position: absolute;
     overflow: visible;
     isolation: isolate;
     height: fit-content;