Feat csv tests

[jtyoung84]

• Makes protected attributes public since they seem to be used a lot in a non-protected manner
• Adds type hints and doc strings
• Adds unit tests for each new method being added
• Uses Enum(str, ...) instead of StrEnum to simplify dependencies and imports
• Fixes a few type hint warnings
• Removes floating class methods. Uses lambda functions to define from_abbreviation methods