fix(PageHeader): Correctly add display prop (#5415)

* correctly add display prop

* correctly update display prop for title

* re-add missing style component

* add :where selector

Co-authored-by: Marie Lucca <[email protected]>

---------

Co-authored-by: Marie Lucca <[email protected]>

Author: randall-krauskopf

.changeset/clever-bears-jog.md

@@ -0,0 +1,5 @@
+---
+"@primer/react": patch
+---
+
+Fix display bug for `PageHeader` component title.

packages/react/src/PageHeader/PageHeader.module.css

@@ -161,12 +161,16 @@
 
 .Title {
   /* using flex and order to display the title in the title area. */
-  display: flex;
+  display: block;
   order: var(--title-area-region-order-title);
   font-size: inherit;
   font-weight: inherit;
 }
 
+.Title:where([data-hidden='true']) {
+  display: none;
+}
+
 .TrailingVisual {
   /* using flex and order to display the trailing visual in the title area. */
   display: flex;

packages/react/src/PageHeader/PageHeader.tsx

@@ -535,6 +535,7 @@ const Title: React.FC<React.PropsWithChildren<TitleProps>> = ({
     <Heading
       className={clsx(enabled && classes.Title, className)}
       data-component="PH_Title"
+      data-hidden={hidden}
       as={as}
       style={style}
       sx={