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/test-samples/integration.groovy

@@ -0,0 +1,22 @@
+@SpringBootTest(classes=Application)
+class BookTests {
+	@Autowired
+	Book book
+	@Test
+	void testBooks() {
+		assertEquals("Tom Clancy", book.author)
+	}
+}
+
+@Configuration
+class Application {
+	@Bean
+	Book book() {
+		new Book(author: "Tom Clancy", title: "Threat Vector")
+	}
+}
+
+class Book {
+	String author
+	String title
+}