msedit: Add at v1.2.1

[Jaredy899]

Summary A simple editor for simple needs.

This editor pays homage to the classic MS-DOS Editor, but with a modern interface and input controls similar to VS Code. The goal is to provide an accessible editor that even users largely unfamiliar with terminals can easily use.

Resolves: https://github.com/getsolus/packages/issues/6567

Test Plan

Tested on Budgie and KDE. Opens and saves.

Checklist

• [x] Package was built and tested against unstable
• [ ] This change could gainfully be listed in the weekly sync notes once merged