macOS: Align scancode conversions with Chromium and Firefox

[madsmtm]

I went spelunking, and found Chromium's and Firefox' conversion tables. So I thought I would check our code against that, and lo and behold, we did indeed have some inconsistencies.

This PR fixes those.

• Tested on all platforms changed
  • Tested as far as possible, given that I don't own keyboards that have most of these keys.
• Added an entry to the changelog module if knowledge of this change could be valuable to users
• Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
• Created or updated an example program if it would help users understand this functionality