feat(cli): complete --config after command

Adds support for completing --config values with _filedir, but only when
they appear after the cargo subcommand.

Author: nspin

src/etc/cargo.bashcomp.sh

@@ -36,7 +36,8 @@ _cargo()
 	local opt_verbose='-v --verbose'
 	local opt_quiet='-q --quiet'
 	local opt_color='--color'
-	local opt_common="$opt_help $opt_verbose $opt_quiet $opt_color"
+	local opt_config='--config'
+	local opt_common="$opt_help $opt_verbose $opt_quiet $opt_color $opt_config"
 	local opt_pkg_spec='-p --package --all --exclude --workspace'
 	local opt_pkg='-p --package'
 	local opt_feat='-F --features --all-features --no-default-features'
@@ -143,6 +144,9 @@ _cargo()
 			--target-dir|--path)
 				_filedir -d
 				;;
+			--config)
+				_filedir
+				;;
 			help)
 				_ensure_cargo_commands_cache_filled
 				COMPREPLY=( $( compgen -W "$__cargo_commands_cache" -- "$cur" ) )