Move UriModifyingOperationPreprocessor to core project

This functionality does not rely on RestAssured, and could prove
useful to other Spring REST Docs extensions.

See gh-493

spring-restdocs-restassured/src/test/java/org/springframework/restdocs/restassured3/operation/preprocess/UriModifyingOperationPreprocessorTests.java

@@ -41,7 +41,9 @@ import static org.junit.Assert.assertThat;
  * Tests for {@link UriModifyingOperationPreprocessor}.
  *
  * @author Andy Wilkinson
+ * @deprecated use {@link org.springframework.restdocs.operation.preprocess.UriModifyingOperationPreprocessorTests} instead
  */
+@Deprecated
 public class UriModifyingOperationPreprocessorTests {
 
 	private final OperationRequestFactory requestFactory = new OperationRequestFactory();