Add support for hyprland/submap

[JSGRD22]

Is your feature request related to a problem? Please describe.
Currently, there is a “sway mode” module for panels that show when sway is in a specific mode, in particular the “resize” mode. Hyprland has a similar feature known as “submaps”. Waybar has support for them, but nwg-panels appears to have no such module.

Describe the solution you'd like
A simple module called hyprland submap as a hyprland counterpart to sway mode. It would be particularly helpful when, for example, a submap for resizing windows is activated.