Motivation for this change

This change adds missing TappingDrag option of libinput.
Description can be found at libinput(4): https://www.mankier.com/4/libinput.

I think it should be disabled by default, but I preserved libinput behavior.
Documentation says "Most devices have tap-and-drag enabled by default."

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Fits CONTRIBUTING.md.