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/support/ui/channel_header.js

@@ -32,7 +32,6 @@ Cypress.Commands.add('uiGetChannelFileButton', () => {
 Cypress.Commands.add('uiGetChannelMenu', (options = {exist: true}) => {
     if (options.exist) {
         return cy.get('#channelHeaderDropdownMenu').
-            find('.dropdown-menu').
             should('be.visible');
     }