Units tests changes

[Vedant1]

• units for each table in the abstraction layer is now a dictionary instead of a list of tuples. col name is the key and unit is the value
• error raised if an ingested column's units are different - same workflow or different
  • same workflow- error in the abstraction layer and no data is loaded into abstraction
  • different workflow - error in backend (sqlite for now) and new data not loaded
• new CI tests for test_env.py, test_core.py and test_sqlalchemy.py
• new plugin reader - metadata json reader (different than existing json and schema readers)
• updated requirements.txt to just be base imports
• new requirements.extras.txt with large package imports for full use of all DSI functions
• updated all 6 CI files with the new requirements.extras.txt