Make popout root fixed on desktop (#5641)

Required for ActionSheet passed to SplitLayout as popout.
Useful for situation when page content is scrolled down below
the fold. Absolutely positioned popout root would stay on top of the
page and won't catch click to propogate it to the body.
If PopoutRoot cannot catch the click then close on click
might not work for ActionSheet as click might not be catched and handled by body
handler in case body is not taken full page size (when it's children
are positioned fixed/absolutely).

Should be pretty safe change as absolutely it was positioned initially
for all cases and lately we changed it to fixed specially for mobile
(see 91f5b01#diff-310629b0806cf5a229d2859420471efd9c563b0c3e2422ecf8a1f82310952180L8-L16).

packages/vkui/src/components/PopoutRoot/PopoutRoot.module.css

@@ -13,10 +13,6 @@
   height: 100%;
 }
 
-.PopoutRoot__popout--absolute {
-  position: absolute;
-}
-
 .PopoutRoot__modal {
   position: fixed;
   left: 0;

packages/vkui/src/components/PopoutRoot/PopoutRoot.tsx

@@ -1,6 +1,5 @@
 import * as React from 'react';
 import { classNames } from '@vkontakte/vkjs';
-import { useAdaptivityWithJSMediaQueries } from '../../hooks/useAdaptivityWithJSMediaQueries';
 import { blurActiveElement, useDOM } from '../../lib/dom';
 import { HasRootRef } from '../../types';
 import { AppRootPortal } from '../AppRoot/AppRootPortal';
@@ -11,18 +10,7 @@ interface PopoutRootPopoutProps {
 }
 
 const PopoutRootPopout = ({ children }: PopoutRootPopoutProps) => {
-  const { isDesktop } = useAdaptivityWithJSMediaQueries();
-
-  return (
-    <div
-      className={classNames(
-        styles['PopoutRoot__popout'],
-        isDesktop && styles['PopoutRoot__popout--absolute'],
-      )}
-    >
-      {children}
-    </div>
-  );
+  return <div className={classNames(styles['PopoutRoot__popout'])}>{children}</div>;
 };
 
 interface PopoutRootModalProps {