fix: improve code formatting and module organization

- Corrected code formatting issues such as inconsistent line breaks and unnecessary trailing commas.
- Reorganized `mod.rs` to ensure proper order of module declarations.
- Fixed misplaced imports in `help.rs` and corrected the rendering method signature.
- Cleaned up unused code lines and moved `dummy` module declaration to its correct position.

harmony-rs/opnsense-config/src/modules/dhcp.rs

@@ -183,4 +183,3 @@ impl<'a> DhcpConfig<'a> {
         self.get_lan_dhcpd().bootfilename = Some(boot_filename.to_string());
     }
 }
-