Int96Converter Truncates Timestamps

[tustvold]

Describe the bug

Int96ArrayConverter takes the INT96 data and converts it to an i64 number of milliseconds since epoch, it then multiplies this by 1_000_000 to convert to a i64 number of nanoseconds since epoch. This loses the nanosecond precision contained within the INT96 data

To Reproduce

Expected behavior

Additional context

Noticed whilst playing with #1661