Parses the channel candidates a browser sent at session mint. Tolerant and capped — it never
throws; anything wrong is dropped and reported in ParsedRealtimeChannelCandidates.Rejected.
Parameters
json: string
The raw JSON array string, or null/undefined when the caller sent none.
Parses the channel candidates a browser sent at session mint. Tolerant and capped — it never throws; anything wrong is dropped and reported in ParsedRealtimeChannelCandidates.Rejected.