Added `@mfgames-writing/opf` and `@mfgames-writing/ncx` (MfGames Writing Tools)

In the process to convert mfgames-writing into a monorepo, two packages were missed. These were @mfgames-writing/opf and @mfgames-writing/ncx which are used to create the OPF and NCX files inside the EPUB files. Along the way, Dylan also normalized some of the formatting, cleaned up a bit of debris still left behind, and normalized the new packages in terms of formatting and testing.

Due to philosophical opinions, we moved the packages back to Gitlab and off Sourcehut.