Fix positional args with new parser

- Better alignment for use of positional args without using
  an option.
- Should work similarly with old parsing framework.
- Change position where missing options are checked.
- Fixes #701

spring-shell-samples/src/main/java/org/springframework/shell/samples/e2e/OptionTypeCommands.java

@@ -216,6 +216,7 @@ public class OptionTypeCommands {
 				.withOption()
 					.longNames("arg1")
 					.type(String.class)
+					.position(0)
 					.required()
 					.and()
 				.withTarget()

spring-shell-samples/src/test/java/org/springframework/shell/samples/e2e/OptionTypeCommandsTests.java

@@ -36,6 +36,13 @@ class OptionTypeCommandsTests extends AbstractSampleTests {
 		assertScreenContainsText(session, "Hello hi");
 	}
 
+	@ParameterizedTest
+	@E2ESource(command = "option-type-string hi")
+	void optionTypeStringPositional(String command, boolean interactive) {
+		BaseShellSession<?> session = createSession(command, interactive);
+		assertScreenContainsText(session, "Hello hi");
+	}
+
 	@ParameterizedTest
 	@E2ESource(command = "option-type-boolean", reg = false)
 	void optionTypeBooleanWithAnno(String command, boolean interactive) {