Make then '-config' parameter global

- `--config` needed to be the first argument, before any subcommands.
  Make `--config` global, so that it can appear at (almost) any place.

src/cli/cli_args.rs

@@ -10,6 +10,7 @@ use clap::Subcommand;
 pub struct CliArgs {
     #[clap(
         long, short,
+        global = true,
         help = "Configuration file.",
     )]
     pub config: Option<String>,