Track Random Seed

[seanlaw]

Following issue #1112, we have shifted our (incorrect) goal from migrating to the new random number generator to simply making the existing legacy random number generator more transparent by:

1. Ensuring that all of STUMPY is derived from the same legacy RNG
2. We display the random seed at the start of each test file, which will help ensure better reproducibility

Unfortunately, the NEW NumPy RNG does NOT produce the same results across different NumPy versions