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-tools/spring-boot-loader/src/it/executable-props-lib/verify.groovy

@@ -0,0 +1,17 @@
+def jarfile = './target/executable-props-lib-0.0.1.BUILD-SNAPSHOT-app.jar'
+
+new File("${basedir}/application.properties").delete()
+
+String exec(String command) {
+	def proc = command.execute([], basedir)
+	proc.waitFor()
+	proc.err.text
+}
+
+String out = exec("java -jar ${jarfile}")
+assert out.contains('Hello Embedded World!'),
+	'Using -jar my.jar should load dependencies from separate jar and use the application.properties from the jar\n' + out
+
+out = exec("java -cp ${jarfile} org.springframework.boot.loader.PropertiesLauncher")
+assert out.contains('Hello Embedded World!'),
+	'Using -cp my.jar with PropertiesLauncher should load dependencies from separate jar and use the application.properties from the jar\n' + out