introduce constant: reuse existing inner class when extracting from enum constant (IDEA-95810)

(cherry picked from commit d5a3ed5aded47303990ca4a3bc70d9817428edf7)

java/java-tests/testData/refactoring/introduceConstant/FromEnumConstantInitializer.java

@@ -3,4 +3,8 @@ enum TestEnum {
 
   TestEnum(String str) {
   }
+  
+  private class Constants {
+    void foo(){}
+  }
 }

java/java-tests/testData/refactoring/introduceConstant/FromEnumConstantInitializer1.java

@@ -0,0 +1,10 @@
+enum TestEnum {
+  ONE("te<caret>stString");
+
+  TestEnum(String str) {
+  }
+
+  private static class Constants {
+    public static final String FOO = "";
+  }
+}

java/java-tests/testData/refactoring/introduceConstant/FromEnumConstantInitializer1_after.java

@@ -0,0 +1,11 @@
+enum TestEnum {
+  ONE(Constants.xxx);
+
+  TestEnum(String str) {
+  }
+
+  private static class Constants {
+    public static final String FOO = "";
+      public static final String xxx = "testString";
+  }
+}

java/java-tests/testData/refactoring/introduceConstant/FromEnumConstantInitializer_after.java

@@ -1,10 +1,14 @@
 enum TestEnum {
-  ONE(Constants.xxx);
+  ONE(Constants1.xxx);
 
   TestEnum(String str) {
   }
 
-    private class Constants {
+    private static class Constants1 {
         public static final String xxx = "testString";
     }
+
+    private class Constants {
+    void foo(){}
+  }
 }