trackPayload
Tracks a payload count. If the payload isn't yet tracked, adds it at 0 (does NOT increment it), else does nothing.
Parameters
payload
The payload to track/increment
isAck
Whether this is an ACK payload (only used if payload doesn't exist yet)
dsc
Device state counter (for ACKs, null for writes, only used if payload doesn't exist yet)
psc
Payload state counter (for writes, or for ACKs that have PSC, only used if payload doesn't exist yet)