App grid should not have to reset with every new app added/removed

## Problem
Installing/removing apps or adding/removing .desktop's will cause the Menu to reset back to page 1. This isn't very user friendly and feels quite janky (and makes the UX feel fragile)

## Proposal

Make the grid it's own container that is able to have items dynamically added/removed when installed, or if the .desktop (or .flatpak?) is dragged-and-dropped on to the Menu.

## Prior Art
The MacOS 'Applications' menu before it sucked: