Site Editor: update headings hierarchy in the 'Manage all' screens (#…

…52271)

* This commit:
- updates heading levels on the template and template part pages
- passes a `level` prop to Header from Page

* update h2 size

* Rolling back custom sizes

* Rolling back unnecessary classNames
There was a rogue space in trunk. Let's let it live

packages/edit-site/src/components/page-template-parts/index.js

@@ -45,7 +45,7 @@ export default function PageTemplateParts() {
 			header: __( 'Template Part' ),
 			cell: ( templatePart ) => (
 				<VStack>
-					<Heading level={ 5 }>
+					<Heading as="h3" level={ 5 }>
 						<Link
 							params={ {
 								postId: templatePart.id,

packages/edit-site/src/components/page-templates/index.js

@@ -46,7 +46,7 @@ export default function PageTemplates() {
 			header: __( 'Template' ),
 			cell: ( template ) => (
 				<VStack>
-					<Heading level={ 5 }>
+					<Heading as="h3" level={ 5 }>
 						<Link
 							params={ {
 								postId: template.id,

packages/edit-site/src/components/page/header.js

@@ -18,7 +18,7 @@ export default function Header( { title, subTitle, actions } ) {
 		<HStack as="header" alignment="left" className="edit-site-page-header">
 			<FlexBlock className="edit-site-page-header__page-title">
 				<Heading
-					as="h1"
+					as="h2"
 					level={ 4 }
 					className="edit-site-page-header__title"
 				>