[2.3.0] Checkmk Werk 15718 created: Improve main menu keyboard navigation

[//]: # (werk v2) # Improve main menu keyboard navigation key | value ---------- | --- date | 2024-01-16T11:21:43+00:00 version | 2.3.0b1 class | feature edition | cre component | multisite level | 2 compatible | yes The main menu of the UI has now more extended support for keyboard navigation. You can open up the menus with the following key combinations: * Monitoring: `ALT + m` * Setup: `ALT + s` * Customize: `ALT + c` The search field is automatically focussed (as before), you can directly insert your search term. By using `TAB` you can navigate the search results and confirm your choice with `ENTER`. Pressing `ESC` for the first time clears the current search term. A second `ESC` closes the open menu. Utilizing the workflow can make navigating to the desired pages in Checkmk much faster.