Align custom scripts with generic scripts (#445)

Align custom scripts with generic scripts, making them configurable. This has a few advantages:

- script code is more unified,
- no more hard-coded method names in scripts, which is less error prone and make it easier to rename scripts,
- no more hard coded product names in scripts, which is less error prone and make it easier to rename products,
- less hard-coded URLs and regexes in scripts, which makes auto-configuration more expressive / updatable,

Also added method `endoflife.list_configs_from_argv()` so that it is easier to manipulate scripts arguments.

src/distrowatch.py

@@ -1,13 +1,7 @@
-import sys
-
 from bs4 import BeautifulSoup
 from common import dates, endoflife, http, releasedata
 
-METHOD = 'distrowatch'
-
-p_filter = sys.argv[1] if len(sys.argv) > 1 else None
-m_filter = sys.argv[2] if len(sys.argv) > 2 else None
-for config in endoflife.list_configs(p_filter, METHOD, m_filter):
+for config in endoflife.list_configs_from_argv():
     with releasedata.ProductData(config.product) as product_data:
         response = http.fetch_url(f"https://distrowatch.com/index.php?distribution={config.url}")
         soup = BeautifulSoup(response.text, features="html5lib")