Add "SHI - Data Gateway" API

[elliot-huffman]

Format: OpenAPI 3.0
Official: YES
Url: https://raw.githubusercontent.com/Software-Hardware-Integration-Lab/OpenAPI/refs/heads/main/specs/Data-Gateway.json
Name: SHI - Data Gateway
Category: backend
Logo: https://www.content.shi.com/SHIcom/images/Global/HeaderFooter/SHI_LOGO_2022_Positive.svg