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/secure.groovy

@@ -0,0 +1,13 @@
+package org.test
+
+@Grab("spring-boot-starter-security")
+@Grab("spring-boot-starter-actuator")
+
+@RestController
+class SampleController {
+
+	@RequestMapping("/")
+	public def hello() {
+		[message: "Hello World!"]
+	}
+}