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/src/test/resources/log4j2-test.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration status="WARN">
+	<Appenders>
+		<Console name="Console" target="SYSTEM_OUT">
+			<PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{1.} - %msg%n" />
+		</Console>
+	</Appenders>
+	<Loggers>
+		<Root level="debug">
+			<AppenderRef ref="Console" />
+		</Root>
+	</Loggers>
+</Configuration>