Convert WeChat Channels channel ID to finder username

Resolves a WeChat Channels publicly visible Channel ID (sph… short ID) into a finder username (v2_…@finder). Send channel_id (WeChat Channels ID (short ID starting with sph)); optional raw. Returns resolved finder username plus account nickname and description. With the username you can then call fetch_user_videos, fetch_channel_info, fetch_user_profile, etc.