docs: DX and performance improvements in API reference (#9430)

- Improve scroll behavior between active sections
- Improve lag when clicking on a sidebar item
- Refactor internal working of the `SidebarProvider` to find active items faster.
- Use Next.js's `useRouter` hook for changing the hash (since they added the option to disable scroll)
- Change `isBrowser` from a hook to a provider since it's widely used across applications.
- Other general improvements and fixes.

Closes DOCS-952

www/packages/docs-ui/src/components/Sidebar/Item/Link/index.tsx

@@ -76,6 +76,12 @@ export const SidebarItemLink = ({
     newTopCalculator,
   ])
 
+  useEffect(() => {
+    if (active && isMobile) {
+      setSidebarOpen(false)
+    }
+  }, [active, isMobile])
+
   const hasChildren = useMemo(() => {
     return !item.isChildSidebar && (item.children?.length || 0) > 0
   }, [item.children])
@@ -108,14 +114,6 @@ export const SidebarItemLink = ({
             "flex justify-between items-center gap-[6px]",
             className
           )}
-          scroll={true}
-          onClick={() => {
-            if (isMobile) {
-              setSidebarOpen(false)
-            }
-          }}
-          replace={!item.isPathHref}
-          shallow={!item.isPathHref}
           {...item.linkProps}
         >
           <span