feat: refactors bergamo mapper

[jtyoung84]

Closes #16

• Updates the interface so that a user defines the job using a pydantic BaseSettings class. The user will need to implement a run_job method
• Adds an extra unit test module for legacy functions that used to be covered by the old bergamo etl tests
• In the future, all jobs should be implemented like:

# not necessary to dump to json, but the option makes it easier to run via a rest request
job_settings_json = user_settings.model_dump_json()
etl_job = BergamoEtl(job_settings=job_settings_json)
job_response = etl_job.run_job()