Add post locked check in isEditedPostSaveable.

So that we can prevent saving if the post is locked.

We also prevent disabling Preview button when the post is not saveable. This is ripple effect of adding isPostLocked check in `isEditedPostSaveable` selector. We can safely remove this check on `Preview` button, because #32341 will prevent any save actions under the hood.

packages/editor/src/components/post-preview-button/index.js

@@ -106,8 +106,8 @@ export default function PostPreviewButton( {
 	role,
 	onPreview,
 } ) {
-	const { postId, currentPostLink, previewLink, isSaveable, isViewable } =
-		useSelect( ( select ) => {
+	const { postId, currentPostLink, previewLink, isViewable } = useSelect(
+		( select ) => {
 			const editor = select( editorStore );
 			const core = select( coreStore );
 
@@ -119,10 +119,11 @@ export default function PostPreviewButton( {
 				postId: editor.getCurrentPostId(),
 				currentPostLink: editor.getCurrentPostAttribute( 'link' ),
 				previewLink: editor.getEditedPostPreviewLink(),
-				isSaveable: editor.isEditedPostSaveable(),
 				isViewable: postType?.viewable ?? false,
 			};
-		}, [] );
+		},
+		[]
+	);
 
 	const { __unstableSaveForPreview } = useDispatch( editorStore );
 
@@ -168,7 +169,6 @@ export default function PostPreviewButton( {
 			className={ className || 'editor-post-preview' }
 			href={ href }
 			target={ targetId }
-			disabled={ ! isSaveable }
 			onClick={ openPreviewWindow }
 			role={ role }
 		>

packages/editor/src/store/selectors.js

@@ -495,6 +495,10 @@ export function isEditedPostSaveable( state ) {
 		return false;
 	}
 
+	if ( isPostLocked( state ) ) {
+		return false;
+	}
+
 	// TODO: Post should not be saveable if not dirty. Cannot be added here at
 	// this time since posts where meta boxes are present can be saved even if
 	// the post is not dirty. Currently this restriction is imposed at UI, but