Add horizontal sorting

[Yaksinikos]

Expected behaviour Sort my starters and files horizontally.

Actual behaviour There is just the option of vertical sorting in the drop-down-menu.

Steps to reproduce the behaviour Right-click on desk and look for sorting.

MATE general version Mate: 1.20.4

Package version Brisk Menu Starter: 0.5.0 Mate-Panel: 1.20.5

Linux Distribution Manjaro Linux 64bit Kernel: 4.19.30-1-Manjaro x86_64