Do not suggest assignment as a subject in postfix templates

#KT-14077 Fixed

idea/src/org/jetbrains/kotlin/idea/codeInsight/postfix/KtPostfixTemplateProvider.kt

@@ -140,7 +140,7 @@ private class KtExpressionPostfixTemplateSelector(
                 it !is KtBlockExpression &&
                 it !is KtDeclarationWithBody &&
                 !it.isEffectivelyDeclaration()
-            }.filter { !it.isSelector && it.parent !is KtUserType && !it.isOperationReference }
+            }.filter { !it.isSelector && it.parent !is KtUserType && !it.isOperationReference && !KtPsiUtil.isAssignment(it) }
             .toList()
 }
 

idea/testData/codeInsight/postfix/parAssignment.kt

@@ -0,0 +1,5 @@
+fun foo(x: Any) {
+    var y: Any
+    // Only 'x' expression is suggested, not 'y = x'
+    y = x.par<caret>
+}

idea/testData/codeInsight/postfix/parAssignment.kt.after

@@ -0,0 +1,5 @@
+fun foo(x: Any) {
+    var y: Any
+    // Only 'x' expression is suggested, not 'y = x'
+    y = (x)
+}

idea/tests/org/jetbrains/kotlin/idea/codeInsight/postfix/PostfixTemplateProviderTestGenerated.java

@@ -113,6 +113,12 @@ public class PostfixTemplateProviderTestGenerated extends AbstractPostfixTemplat
         doTest(fileName);
     }
 
+    @TestMetadata("parAssignment.kt")
+    public void testParAssignment() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("idea/testData/codeInsight/postfix/parAssignment.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("return.kt")
     public void testReturn() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("idea/testData/codeInsight/postfix/return.kt");