feat(args): add Args#finished (#125)

Co-authored-by: Jeroen Claassens <support@favware.tech>
Co-authored-by: Antonio Román <kyradiscord@gmail.com>

src/lib/utils/Args.ts

@@ -516,6 +516,13 @@ export class Args {
 		if (this.states.length !== 0) this.parser.restore(this.states.pop()!);
 	}
 
+	/**
+	 * Whether all arguments have been consumed.
+	 */
+	public get finished() {
+		return this.parser.finished;
+	}
+
 	/**
 	 * Resolves an argument.
 	 * @param arg The argument name or [[IArgument]] instance.