DOLfYN: Standardize all reader output types and units

[simmsa]

Current Status: Work in Progress

• Add ADCP/ADV test files from latest MHKiT-Python
• Split reader tests into multiple files
• Add comparison function to tests to check for any "significant" differences

Long term goal is to also add RDI readers detailed in issue #180. This is likely out of scope of this specific PR, but is meant to lay the foundation for that work.