Issues with the parse iso time functions

We see some issues in the parse iso time functions which are currently in the run_neon.py script. We are in process to move it to the utils module. We added a simple unit test for its current functionality.

Some assumptions it makes that we should examine:

- Only handles no-leap calendars
- Assumes 30 day months which is really problematic if time duration has months
- Lack of error checking
- get_isosplit returns the number as string, and iso_string as an empty string, which doesn't seem useful

Currently it is only used for durations of even years, so this all may be fine for the purposes we need it for.