Bindable keyboard shortcuts to add system tags

[novakda]

When doing multiple searches with system tags (e.g. system:hash), it can be cumbersome to locate and add the them to the current search.

Please consider adding keyboard shortcuts to allow adding a system tag to the current search.

For example, a keyboard shortcut to for system:hash would act the same as double-clicking on it in the search results box (open the input predicate dialog, and add hashes to the search if the dialog is confirmed).