feat: Rename 'validate-config' task to 'appmap-validate-config'

Author: kgilpin

src/main/java/com/appland/appmap/gradle/AppMapPlugin.java

@@ -69,7 +69,7 @@ private void addAppMapTasks(AppMapPluginExtension extension) {
         });
 
     project.getTasks().register(
-        "validate-config",
+        "appmap-validate-config",
         validateConfigTask -> {
           validateConfigTask.doFirst(
               new ValidateConfigAction(extension.getConfigFile().getAsFile())