Issue 3: create flow alert package

This creates the initial package structure for flow alert:

• the package is located at src/flowalert
• tests are located at src/test
• the environment, which is defined in the pyproject.toml file can be created with poetry poetry install
  • NOTE: I added all dependencies that I saw; however, I do not know where read_file_path_csv is supposed to come from.
• the documentation folder is located at docs

closes #3 (closed)