[MM-36428][MM-36434][MM-36435] Keyboard navigation and menu updates for new tab/dropdown layout (#1695)

* [MM-36428][MM-36434][MM-36435] Keyboard navigation and menu updates for new tab/dropdown layout

* Shortcuts for Windows/Linux

* Update config.yml

* Fixed up the shortcuts

* Fixed the new server modal popping up where there are GPO teams only

src/renderer/components/MainPage.tsx

@@ -400,6 +400,7 @@ export default class MainPage extends React.PureComponent<Props, State> {
                         <DotsVerticalIcon/>
                     </button>
                     <TeamDropdownButton
+                        isDisabled={this.state.modalOpen}
                         activeServerName={this.state.activeServerName}
                         totalMentionCount={totalMentionCount}
                         hasUnreads={totalUnreadCount > 0}