Create a nice DMG installer

[marcus-crane]

A basic one can be added to the pipeline without too much friction using create-dmg

create-dmg --volname "October" --window-pos 200 120 --window-size 800 400 --icon-size 100 --icon "October.app" 200 190 --hide-extension "October.app" --app-drop-link 600 185 "October.dmg" .

The only catch is that the app would need to be codesigned first and Gon used in notarisation only mode against the dmg. Thankfully I've done this one time before so I have a working example.

[marcus-crane]

I need to refactor how notarisation works, as Gon is using a now-deprecated workflow which should unlock the ability to make a nicer dmg