refactor: update obsolete keycodes

[lesshonor]

Board/Shield Check-list

• [x] Keymaps do not use deprecated key defines (Check using the upgrader tool)

There are a fair number of keymaps which still use deprecated keycodes. I think it's a good idea for new repositories not to start off with obsolete keycodes straight out of ZMK main.

...A lot of keymaps have decorative ASCII comments which also use obsolete keycodes. I think these are a bad idea but clearly others disagree—so I split the difference by updating commented-out keycodes where they wouldn't disturb the alignment, or if I already had to modify the file. The commit that touches any of the comments can be dropped if desired.