System-wide replay running at the clock used in the replayed log (rather than the system time of host)

[wangwwno1]

Describe problem solved by the proposed feature

Existing replay module only align the timestamp of each message (timestamp field) to the current system time. This create a discrepancy to other timestamps (e.g., timestamp_sample) and does not consistent with the goal: to replay the flight log as-is.

Describe your preferred solution

At the start of the replay, the replay module calculate the time offset between the system time and the log file timestamp.
In replay mode, we can take this offset as the hrt_absolute_time_offset. When the firmware calls hrt_absolute_time, it returns the timestamp relative to the clock used in the flight log (rather than the host system time).

Describe possible alternatives

1. Make other timestamps relative to the main timestamp, as suggested in the doc.
2. Identify timestamp fields with rules (e.g., prefix) and align them to the current system time.
3. Use lockstep to manage the system time update.

Additional context

No response