Add unrecognised option support

- This commit modifies CommandParser to better track positional parameters
  which previously used to go there for non-recognised options. Now using
  relatively dump logic of just checking if first positional parameter starts
  with '-' which indicates it's a candidate for a new `UnrecognisedOptionException`
  which then would give user an error "Unrecognised option '--xxx'" for example.
- Fixes #601
- Fixes #602

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

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.shell.samples.e2e;
+
+import java.util.function.Supplier;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.shell.command.CommandRegistration;
+import org.springframework.shell.standard.ShellComponent;
+import org.springframework.shell.standard.ShellMethod;
+import org.springframework.shell.standard.ShellOption;
+
+@ShellComponent
+public class UnrecognisedOptionCommands extends BaseE2ECommands {
+
+	@ShellMethod(key = LEGACY_ANNO + "unrecognised-option-noother", group = GROUP)
+	public String testUnrecognisedOptionNoOtherAnnotation(
+	) {
+		return "Hi";
+	}
+
+	@Bean
+	public CommandRegistration testUnrecognisedOptionNoOtherRegistration(Supplier<CommandRegistration.Builder> builder) {
+		return builder.get()
+			.command(REG, "unrecognised-option-noother")
+			.group(GROUP)
+			.withTarget()
+				.function(ctx -> {
+					return "Hi";
+				})
+				.and()
+			.build();
+	}
+
+	@ShellMethod(key = LEGACY_ANNO + "unrecognised-option-withrequired", group = GROUP)
+	public String testUnrecognisedOptionWithRequiredAnnotation(
+		@ShellOption(help = "Desc arg1") String arg1
+	) {
+		return "Hello " + arg1;
+	}
+
+	@Bean
+	public CommandRegistration testUnrecognisedOptionWithRequiredRegistration(Supplier<CommandRegistration.Builder> builder) {
+		return builder.get()
+			.command(REG, "unrecognised-option-withrequired")
+			.group(GROUP)
+			.withOption()
+				.longNames("arg1")
+				.description("Desc arg1")
+				.required()
+				.and()
+			.withTarget()
+				.function(ctx -> {
+					String arg1 = ctx.getOptionValue("arg1");
+					return "Hello " + arg1;
+				})
+				.and()
+			.build();
+	}
+}