Move GraphQlArgumentInitializer to data package

Following the changes in #191, GraphQlArgumentInitializer is no longer
package private and also needs to be used in the DataFetcher for
Query By Example. As a first step, this change moves the class to
the top-level data package that is a parent of both.

See gh-191

spring-graphql/src/main/java/org/springframework/graphql/data/GraphQlArgumentInitializer.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package org.springframework.graphql.data.method.annotation.support;
+package org.springframework.graphql.data;
 
 import java.lang.reflect.Constructor;
 import java.util.Collection;

spring-graphql/src/main/java/org/springframework/graphql/data/method/annotation/support/ArgumentMethodArgumentResolver.java

@@ -25,6 +25,7 @@ import org.springframework.core.CollectionFactory;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
+import org.springframework.graphql.data.GraphQlArgumentInitializer;
 import org.springframework.graphql.data.method.HandlerMethodArgumentResolver;
 import org.springframework.graphql.data.method.annotation.Argument;
 import org.springframework.lang.Nullable;

spring-graphql/src/main/java/org/springframework/graphql/data/querybyexample/QueryByExampleDataFetcher.java

@@ -57,7 +57,7 @@ import org.springframework.data.repository.query.ReactiveQueryByExampleExecutor;
 import org.springframework.data.util.ClassTypeInformation;
 import org.springframework.data.util.TypeInformation;
 import org.springframework.graphql.data.GraphQlRepository;
-import org.springframework.graphql.data.method.annotation.support.GraphQlArgumentInitializer;
+import org.springframework.graphql.data.GraphQlArgumentInitializer;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;

spring-graphql/src/test/java/org/springframework/graphql/data/method/annotation/support/GraphQlArgumentInitializerTests.java

@@ -27,6 +27,7 @@ import graphql.schema.DataFetchingEnvironmentImpl;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.graphql.Book;
+import org.springframework.graphql.data.GraphQlArgumentInitializer;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;