Added 2 handwired keyboards

[andresteare]

Description

Added 2 handwired keyboard:

Gamdias 7 colors fullsize iso keyboard
IBM 6715 typewriter with (buckling springs!)

Note on the IBM one: both shift keys share the same circuit so, to avoid any confussion, I excluded RShift from the keymap (I put bigger warning in the README)

I started with the idea of supporting the community because I gave the Gamdias to a friend who doesn't even know what QMK is so having the keyboard officially supported by VIA would be very helpful

QMK Pull Request

qmk/qmk_firmware#11696

Checklist

• The QMK source code follows the guide here: https://caniusevia.com/docs/configuring_qmk
• The VIA definition follows the guide here: https://caniusevia.com/docs/layouts
• I have tested this keyboard definition using VIA's "Design" tab.
• I have tested this keyboard definition with firmware on a device.
• I have assigned alpha keys and modifier keys with the correct colors.
• The Vendor ID is not 0xFEED

[andresteare]

both build are already merged in QMK, so I think it's ready :)