[KxSerialization] Implemented generation of companions for interfaces

For interfaces with custom serializer (@Serializer(`SerializerType::class)`) now the `serializer()` function is generated in the companion so that user can get a serializer by type

Merge-request: KT-MR-11040
Merged-by: Sergey Shanshin <Sergey.Shanshin@jetbrains.com>

plugins/kotlinx-serialization/tests-gen/org/jetbrains/kotlinx/serialization/runners/SerializationFirJsBoxTestGenerated.java

@@ -49,6 +49,12 @@ public class SerializationFirJsBoxTestGenerated extends AbstractSerializationFir
         runTest("plugins/kotlinx-serialization/testData/boxIr/excludedFromFileExport.kt");
     }
 
+    @Test
+    @TestMetadata("interfaces.kt")
+    public void testInterfaces() throws Exception {
+        runTest("plugins/kotlinx-serialization/testData/boxIr/interfaces.kt");
+    }
+
     @Test
     @TestMetadata("serializerFactory.kt")
     public void testSerializerFactory() throws Exception {

plugins/kotlinx-serialization/tests-gen/org/jetbrains/kotlinx/serialization/runners/SerializationFirLightTreeBlackBoxTestGenerated.java

@@ -141,6 +141,12 @@ public class SerializationFirLightTreeBlackBoxTestGenerated extends AbstractSeri
             runTest("plugins/kotlinx-serialization/testData/boxIr/inlineClasses.kt");
         }
 
+        @Test
+        @TestMetadata("interfaces.kt")
+        public void testInterfaces() throws Exception {
+            runTest("plugins/kotlinx-serialization/testData/boxIr/interfaces.kt");
+        }
+
         @Test
         @TestMetadata("intrinsicAnnotations.kt")
         public void testIntrinsicAnnotations() throws Exception {

plugins/kotlinx-serialization/tests-gen/org/jetbrains/kotlinx/serialization/runners/SerializationIrBoxTestGenerated.java

@@ -139,6 +139,12 @@ public class SerializationIrBoxTestGenerated extends AbstractSerializationIrBoxT
         runTest("plugins/kotlinx-serialization/testData/boxIr/inlineClasses.kt");
     }
 
+    @Test
+    @TestMetadata("interfaces.kt")
+    public void testInterfaces() throws Exception {
+        runTest("plugins/kotlinx-serialization/testData/boxIr/interfaces.kt");
+    }
+
     @Test
     @TestMetadata("intrinsicAnnotations.kt")
     public void testIntrinsicAnnotations() throws Exception {

plugins/kotlinx-serialization/tests-gen/org/jetbrains/kotlinx/serialization/runners/SerializationIrJsBoxTestGenerated.java

@@ -49,6 +49,12 @@ public class SerializationIrJsBoxTestGenerated extends AbstractSerializationIrJs
         runTest("plugins/kotlinx-serialization/testData/boxIr/excludedFromFileExport.kt");
     }
 
+    @Test
+    @TestMetadata("interfaces.kt")
+    public void testInterfaces() throws Exception {
+        runTest("plugins/kotlinx-serialization/testData/boxIr/interfaces.kt");
+    }
+
     @Test
     @TestMetadata("serializerFactory.kt")
     public void testSerializerFactory() throws Exception {