Applies the opt-out gate: an account in the opt-out state is not sent
events while risc.honourOptOut is on, except the four opt-out events,
which are never suppressed.
Parameters
row: RiscRow
the account's row
uri: string
the event type URI
Returns {send:boolean;why:string}
{ send, why }; why says why an event was suppressed
Applies the opt-out gate: an account in the
opt-outstate is not sent events whilerisc.honourOptOutis on, except the four opt-out events, which are never suppressed.