(Not Checked) IPTA Unit Tests

[JamisonTalley]

This is an update to the tests directory in pint_pal that performs unit tests on most of the common methods used in the IPTA notebooks. These tests all pass on my versions of PINT and Pint Pal, but that is only one environment on one machine, so they probably need to be checked on the system that will actually be running the tests. Something to note is that there are scripts in the tests directory that have yet to be updated, and are likely incompatible with the current version of the software. There are more tests that may be helpful (see the commented out tests in test_lite_utils.py, for example), but I have yet to complete them.

This PR is prefaced as a Not Checked because it has not been cross-checked on a different system, but if these changes work on the testing system, they should be ready to merge. There was some discussion as to which branch the tests should be merged into, so this PR can be tweaked or recreated to fit whatever decision is made.

[JPGlaser]

@rossjjennings and @JamisonTalley , we need to include these tests into the GitHub Actions. Once its done and they successfully are tested by pytest, we can do a merge.

~ Joe G.