heartbeat calculation improvement based on heartbeat request sequence and timestamp

[JaydenLiang]

internal issue id: 0741713

It will make use of the two new properties in the incoming heartbeat request sending from FOS (at earliest 7.0.2)

Example request body:
{"instance": "i-0bd8fd4d2a36a841f", "interval": 30, "sequence":968, "time":"2021-08-19T04:40:38Z"}

use the new properties to determine heartbeat sequence and timing in order to keep or discard a certain heartbeat request.

the change should be compatible with existing FOS versions (7.0.1 and older) which send the heartbeat request in the format:
{"instance": "i-0bd8fd4d2a36a841f", "interval": 30}

code should not break without the presence of the new properties.