Create 1upslider8.json

[ziptyze]

First commit of the configuration for the 1upkeyboards slider8 macropad

Description

Configuration for the 1upkeyboards slider8 macropad, a 2x4 ortholinear macro pad with an oled, midi slider, and rotary encoder with per-key RGB. The keyboard is offered as a solder kit, and uses a pi pico as a controller

QMK Pull Request

qmk/qmk_firmware#21546

Checklist

• The VIA support for this keyboard is MERGED in QMK 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 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