reorganize into flows, tasks, and functions

[groovecoder]

Refactors into a new module structure for using https://www.prefect.io:

├──  data_models  // pydantic models
├──  flows        // prefect flows
├──  functions    // core functions
├──  local        // local data and models when running in "local" mode
├──  scripts      // main callable scripts
├──  tasks        // prefect tasks
└── 󰙨 tests        // tests

[groovecoder]

Closing to re-do this branch on latest main.