Create What's New Popup that tells users what's changed the first time they run a new version.

[1hitsong]

Changes
Creates a popup that shows the first time a user runs a new version of the client. This popup shows what's changed in this version.

Creates a user setting that allows users to disable the popup so they don't see it even when running a new version for the first time.

Demo:
https://social.linux.pizza/@tgpo/109553679336510552

[jimdogx]

Works. But I have questions:

1. Will there be a github action that auto-magically generates the WhatsNew.json file? Or will we need to remember (i.e. have a process in place to not forget) to update this file manually?
2. Do we want a way for a user to re-launch the pop-up? Something under the main menu options perhaps?

[1hitsong]

1. My thought was we'd start with it manual until one of us made it automatic - if it's possible.
2. I was thinking about that the other day. How would users know to relaunch it unless they periodically checked it. My though was potentially adding a version number and/or release date to the bottom of the options menu on the homepage. They can easily press the button and see if it's what they expected.