Promote Norman layout from extras to base.

I had a sort of humbling experience this month when one of my friends said they were building their own DIY keyboard from a PCB up and they found someone who was printing Norman keycaps to apply to it. I looked up from my daily routine and it sort of looks like Norman has become at least as popular as Workman, which is in the base XML for keyboard layouts. This merge would shift the visibility of Norman.

MT3 Serika keycaps for DIY keyboards: "Finally, the Typist kit provides layout coverage for Colemak, Colemak DH, Colemak DHM, Dvorak, Workman, Norman, and Carpalx QGMLWY."" https://web.archive.org/web/20190830135956/https://zambumon.com/portfolio/mt3-serika/

Ergodox-EZ sales pitch: "They are all the same profile so you can easily move them around for Colemak, Norman, or any other layout."" https://web.archive.org/web/20190719210949/https://ergodox-ez.com/

MK Keyboard programmable keyboard: "Over 10 built-in layouts including: QWERTY, Norman, Workman, Dvorak, MiniMak, Alphabetical, and more" https://web.archive.org/web/20190325234616/https://mechanicalkeyboards.com/shop/index.php?l=product_detail&p=4295&mkref=wvr4aaa

Type-Fu typing practice Mac app: "English language users can choose between following layouts: Qwerty, Dvorak, Colemak, Workman, Norman, Qwertz, Azerty." https://apps.apple.com/us/app/type-fu/id509818877?ls=1&mt=12

Norman keyboard in Chocolatey for Windows: https://chocolatey.org/packages/norman/0.0.1

Confusion from someone who couldn't find Norman buried in Extras and was frustrated enough to make a bugzilla account to say so: https://bugs.freedesktop.org/show_bug.cgi?id=71453#c8