[IMPROVE] Add CTRL modifier for keyboard shortcut (#12525)

* Add CTRL modifier for keyboard shortcut

As pointed out in #12519 Chrome already uses `Shift+ESC`, colliding
with the 'mark all messages as read' keyboard shortcut in
RocketChat. This change adds the `CTRL` modifier to the shortcut,
i.e. mapping

     Shift+ESC | CTRL+ESC

* Add documentation for keyboard shortcut

This change adds (english) documentation for the keyboard shortcut.

packages/rocketchat-i18n/i18n/en.i18n.json

@@ -1757,6 +1757,7 @@
   "MapView_Enabled_Description": "Enabling mapview will display a location share button on the left of the chat input field.",
   "MapView_GMapsAPIKey": "Google Static Maps API Key",
   "MapView_GMapsAPIKey_Description": "This can be obtained from the Google Developers Console for free.",
+  "Mark_all_as_read": "Mark all messages as read",
   "Mark_as_read": "Mark As Read",
   "Mark_as_unread": "Mark As Unread",
   "Markdown_Headers": "Allow Markdown headers in messages",
@@ -2937,4 +2938,4 @@
   "Your_push_was_sent_to_s_devices": "Your push was sent to %s devices",
   "Your_server_link": "Your server link",
   "Your_workspace_is_ready": "Your workspace is ready to use 🎉"
-}
+}

packages/rocketchat-slashcommands-help/server.js

@@ -13,6 +13,9 @@ RocketChat.slashCommands.add('help', function Help(command, params, item) {
 	const keys = [{
 		Open_channel_user_search: 'Command (or Ctrl) + p OR Command (or Ctrl) + k',
 	},
+	{
+		Mark_all_as_read: 'Shift (or Ctrl) + ESC',
+	},
 	{
 		Edit_previous_message: 'Up Arrow',
 	},

packages/rocketchat-ui-master/client/main.js

@@ -24,7 +24,7 @@ Template.body.onRendered(function() {
 			toolbarSearch.show(true);
 		}
 		const unread = Session.get('unread');
-		if (e.keyCode === 27 && e.shiftKey === true && (unread != null) && unread !== '') {
+		if (e.keyCode === 27 && (e.shiftKey === true || e.ctrlKey === true) && (unread != null) && unread !== '') {
 			e.preventDefault();
 			e.stopPropagation();
 			modal.open({