MM-59065 - New channel menu using new menu system (#30093)

* New channel menu using new menu system

* fix e2e-tests

* remove extraneous separator

* lint fix

* fix test after merge

* update to pass properties to first menu item

* fix e2etest

* refactor: Update channel header menu items to use const event handlers

* refactor: Extract plugin item click handler in channel header menu

* refactor: Improve error handling and button click handlers in mobile channel header plugins

* lint fixes

* updates for code reveiw

* run i18n-extract

* fix unit test

* fix: Close channel dropdown menu by clicking channel header title

* fix: Use keyboard escape to close channel dropdown menu in e2e tests

* fix cypress test

* fix: Resolve MUI Menu component fragment rendering issue

* cleanup

* remove unneccessary css

* fixing testing issues

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

e2e-tests/cypress/tests/integration/channels/account_settings/profile/nickname_spec.ts

@@ -100,7 +100,8 @@ describe('Settings > Sidebar > General', () => {
             cy.uiClose();
 
             // # Open channel menu and click 'Add Members'
-            cy.uiOpenChannelMenu('Add Members');
+            cy.uiOpenChannelMenu('Members');
+            cy.uiGetButton('Add').click();
 
             // * Verify that the modal is open
             cy.get('#addUsersToChannelModal').should('be.visible').findByText(`Add people to ${channel.display_name}`);