Add module for aligning local timestamps to the Harp clock

[jsiegle]

Re-opening after rebasing on main branch:

When acquiring data from a device that is not synchronized to the global Harp clock, Harp timestamps can be encoded as barcodes that are acquired by one of the device's digital input lines. This allows post-hoc synchronization with the Harp clock.

This PR adds a module that can decode the Harp times (in seconds) from set of digital line transitions acquired by a non-Harp device, and use this info to align any of that device's timestamps to the global Harp clock.

This is not directly related to reading data saved by Harp devices, but it's utility that will be needed for a wide range of experiments involving Harp.