RequireThis rule and fixThis Gradle task

* `gradlew clean check -x test --parallel --continue` - to collect reports
* `gradlew fixThis --parallel` - to fix all possible vulnerabilities. With `-Dfile.encoding=UTF-8` on Windows

Since the `RequireThisCheck` doesn't see parents for anonymous classes (e.g. `Runnable` callback), its report doesn't contains the outer class name with `this.`,
therefore we still have to fix those cases manually.
Thanks to the wrong `replacer` just with `this.` we have uncompilable code enough easy to find problems.
Not so easy to fix for good readability though...

* Upgrade to Grade 2.12
* Upgrade to SonarQube native plugin

The fix contains at about 300 files. So, will be done on merge.

Fix `fixThis.gradle` according PR comments

Apply `fixThis` and also `fixModifiers` for test classes.
 Fix some `this.` inner issues manually.
 Make code polishing for long lines after `fixThis`

Fix conflicts and vulnerabilities after the rebase

spring-integration-groovy/src/main/java/org/springframework/integration/groovy/config/GroovyControlBusFactoryBean.java

@@ -89,7 +89,7 @@ public class GroovyControlBusFactoryBean extends AbstractSimpleMessageHandlerFac
 			processor.setCustomizer(this.customizer);
 		}
 		if (this.beanClassLoader != null) {
-			processor.setBeanClassLoader(beanClassLoader);
+			processor.setBeanClassLoader(this.beanClassLoader);
 		}
 		if (getBeanFactory() != null) {
 			processor.setBeanFactory(getBeanFactory());