Add pageUtils dependency and enhance block hiding test for mobile viewport

- Introduced pageUtils to facilitate key presses in the block hiding test.
- Added functionality to open List View before switching to mobile preview to maintain block selection when hidden.
- Included a comment referencing the related GitHub issue for clarity.

Author: ramonjd

test/e2e/specs/editor/various/block-hiding.spec.js

@@ -193,6 +193,7 @@ test.describe( 'Block Hiding', () => {
 	test( 'should hide a block only on Mobile viewport', async ( {
 		page,
 		editor,
+		pageUtils,
 	} ) => {
 		// Insert a paragraph block.
 		await editor.insertBlock( {
@@ -215,6 +216,13 @@ test.describe( 'Block Hiding', () => {
 			.getByRole( 'button', { name: 'Apply' } )
 			.click();
 
+		/*
+		 * Open List View so switching device preview does not clear selection for a block
+		 * that becomes hidden in the target viewport (inspector needs a selected block).
+		 * See: https://github.com/WordPress/gutenberg/issues/76275
+		 */
+		await pageUtils.pressKeys( 'access+o' );
+
 		// Toggle to mobile preview.
 		await page
 			.getByRole( 'region', { name: 'Editor top bar' } )