fix: Use cross-platform shortcuts in ui-tests (#1964)

Previously, UI tests failed on macOS because the required keyboard
shortcuts are slightly different on macOS from Windows and Linux. This
commit updates them to use the ControlOrMeta key, which handles both
cases.

Author: shreve

nbgrader/tests/ui-tests/assignment_list.spec.ts

@@ -151,7 +151,7 @@ const openAssignmentList = async (page: IJupyterLabPageFixture) => {
     mainPanelTabCount
   );
 
-  await page.keyboard.press("Control+Shift+c");
+  await page.keyboard.press("ControlOrMeta+Shift+c");
   await page
     .locator(
       '#modal-command-palette li[data-command="nbgrader:open-assignment-list"]'

nbgrader/tests/ui-tests/course_list.spec.ts

@@ -98,7 +98,7 @@ const openCoursesList = async (page: IJupyterLabPageFixture) => {
     mainPanelTabCount
   );
 
-  await page.keyboard.press("Control+Shift+c");
+  await page.keyboard.press("ControlOrMeta+Shift+c");
   await page
     .locator(
       '#modal-command-palette li[data-command="nbgrader:open-course-list"]'

nbgrader/tests/ui-tests/formgrader.spec.ts

@@ -227,7 +227,7 @@ const openFormgrader = async (page: IJupyterLabPageFixture) => {
     mainPanelTabCount
   );
 
-  await page.keyboard.press("Control+Shift+c");
+  await page.keyboard.press("ControlOrMeta+Shift+c");
   await page
     .locator(
       '#modal-command-palette li[data-command="nbgrader:open-formgrader"]'