add "Collapse all categories" to shortcut configuration

The built-in ctrl/cmd + shift + A shortcut to collapse all categories in community's navigation side-panel works by default, but is not listed in keyboards shortcut list (ctrl + /), nor is an option in the shortcuts configuration to disable built-in shortcut or add custom shortcut.

Add shortcut for "Collapse all categories" to shortcuts configuration (custom shortcut + disable built-in capability) and keyboards shortcut list (ctrl + /). Likely as a Miscellaneous category item. Already exists as a built-in shortcut.