Move integration tests to dedicated module

This commit moves the dependency management and test source files
related to integration tests to a dedicated module.
This allows us to focus the root project on building the Spring
Framework.

See gh-23282

integration-tests/integration-tests.gradle

@@ -0,0 +1,20 @@
+description = "Spring Integration Tests"
+
+dependencies {
+	testCompile(project(":spring-aop"))
+	testCompile(project(":spring-beans"))
+	testCompile(project(":spring-context"))
+	testCompile(project(":spring-core"))
+	testCompile(project(":spring-expression"))
+	testCompile(project(":spring-jdbc"))
+	testCompile(project(":spring-orm"))
+	testCompile(project(":spring-test"))
+	testCompile(project(":spring-tx"))
+	testCompile(project(":spring-web"))
+	testCompile("javax.inject:javax.inject:1")
+	testCompile("javax.resource:javax.resource-api:1.7.1")
+	testCompile("javax.servlet:javax.servlet-api:4.0.1")
+	testCompile("org.aspectj:aspectjweaver:${aspectjVersion}")
+	testCompile("org.hsqldb:hsqldb:${hsqldbVersion}")
+	testCompile("org.hibernate:hibernate-core:5.1.17.Final")
+}