Update support for s6xty

[trnthsn]

Description

QMK Pull Request

QMK pull request

VIA Keymap Pull Request

VIA keymap pull request

Checklist

• The VIA support for this keyboard is MERGED in QMK master already (MANDATORY)
• VIA keymap is MERGED in VIA userspace master already (MANDATORY)
• The VIA definition follows the guide here: https://caniusevia.com/docs/layouts
• I have a V3 JSON version for this keyboard definition.(MANDATORY)
• I have formatted the JSON file to have consistent formatting with the rest of the repository.
• 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

[Cipulot]

On hold till QMK merge, then subsequent via keymap merge.

[Cipulot]

File name could also be changed from trnthsn_s6xty_via.json to s6xty.json.