refactor: revise project structure, models and function names (#31)

* Add `utils` module

* Refactor `main` to `core` module

* Store format related functions in `format/`

* Refactor `cli` to `main` module

* Add logger config

* Call `cli()` function in entry point

* Refactor `normalize` to `normalize_entries`

* Refactor `get_available_formatversions` to `get_formatversion_dirs`

* Refactor `determine_consecutive_formatv.` to `get_formatversion_pairs`

* Refactor `get_matching_pruefid_files` to `get_matching_csv_files`

* Refactor `_populate_row_values` to `_populate_row_entries`

* Refactor `_process_files` to `_process_csv_files`

* Refactor `process_ahb_data` to `process_ahb_files`

* Refactor `_get_csv_content` to `load_csv_dataframes`

* Refactor `get_pruefid_files` to `get_csv_files`

* Refactor `test_export` to `test_dataframe_export_formats`

* Outsource CLI tests

* Refactor `test_export` to `test_data_export`

* Refactor `test_parse_ahb_data` to `test_ahb_parser`

* Refactor `test_process_csv` to `test_csv_processor`

pyproject.toml

@@ -27,7 +27,7 @@ dependencies = [
 dynamic = ["version"]
 
 [project.scripts]
-ahlbatross = "ahlbatross.cli:cli"
+ahlbatross = "ahlbatross.main:cli"
 
 [project.urls]
 Changelog = "https://github.com/Hochfrequenz/ahlbatross/releases"