Refactor scripts arguments handling (#456)

- remove the use of environment variables to get directory paths,
- make use of arguments / argparse instead of environment variables in `update.py` and `report.py`,
- automatically guess the data directory in `latest.py` based on the script's location,
- propagate log level to auto scripts,
- move `list_configs_from_argv` from `endoflife` module to `releasedata` module,
- use `list_products` in `latest.py` to load the product's frontmatters.

src/plesk.py

@@ -1,11 +1,11 @@
-from common import dates, endoflife, http, releasedata
+from common import dates, http, releasedata
 
 """Fetches versions from Plesk's change log.
 
 Only 18.0.20.3 and later will be picked up, as the format of the change log for 18.0.20 and 18.0.19 are different and
 there is no entry for GA of version 18.0.18 and older."""
 
-for config in endoflife.list_configs_from_argv():
+for config in releasedata.list_configs_from_argv():
     with releasedata.ProductData(config.product) as product_data:
         html = http.fetch_html(config.url)