CategoryController: move to ru.mystamps.web.feature.category package.

Addressed to #927

No functional changes.

Author: php-coder

src/main/java/ru/mystamps/web/config/ControllersConfig.java

@@ -27,6 +27,7 @@
 
 // CheckStyle: ignore AvoidStarImportCheck for next 1 line
 import ru.mystamps.web.controller.*; // NOPMD: UnusedImports
+import ru.mystamps.web.feature.category.CategoryController;
 
 @Configuration
 @RequiredArgsConstructor

src/main/java/ru/mystamps/web/controller/CategoryController.java renamed to src/main/java/ru/mystamps/web/feature/category/CategoryController.java

@@ -15,7 +15,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */
-package ru.mystamps.web.controller;
+package ru.mystamps.web.feature.category;
 
 import java.io.IOException;
 import java.util.List;

src/main/java/ru/mystamps/web/feature/category/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Categories of the stamp series.
+ */
+package ru.mystamps.web.feature.category;