Enhance/refactor previously implemented Time History File update utility to be more generalized/useful

[Lagejohn]

#22 involved the creation and use of a TimeHistUpdater.py script in the internal testing repo for quickly updating all of the time history files in the regression test datasets. It's currently hardcoded to only update values in the "Enc_SCLK" column from scientific notation to integer format, but could be improved to more generally replace or transform values in our regression test datasets all at once, drastically cutting down on the manual work required to keep regression tests passing whenever an output product is changed.