Relocate projects to spring-boot-project

Move projects to better reflect the way that Spring Boot is released.

The following projects are under `spring-boot-project`:

  - `spring-boot`
  - `spring-boot-autoconfigure`
  - `spring-boot-tools`
  - `spring-boot-starters`
  - `spring-boot-actuator`
  - `spring-boot-actuator-autoconfigure`
  - `spring-boot-test`
  - `spring-boot-test-autoconfigure`
  - `spring-boot-devtools`
  - `spring-boot-cli`
  - `spring-boot-docs`

See gh-9316

spring-boot-project/spring-boot-cli/samples/web.groovy

@@ -0,0 +1,21 @@
+@Controller
+class Example {
+
+	@Autowired
+	private MyService myService;
+
+	@RequestMapping("/")
+	@ResponseBody
+	public String helloWorld() {
+		return myService.sayWorld();
+	}
+
+}
+
+@Service
+class MyService {
+
+	public String sayWorld() {
+		return "World!";
+	}
+}