feat: Add `forbidden_filename_basenames` config option

This allows to configure forbidden filenames (the full filename like `.htaccess`)
and also forbidden basenames like `com0` where `com0`, `com0.txt` and `com0.tar.gz` will match.
We need this as only using basenames was too restrictive and will cause problems on some systems when updating.

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>