[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/kotlinx-serialization.k1/src/org/jetbrains/kotlinx/serialization/compiler/resolve/KSerializationUtil.kt

@@ -113,7 +113,11 @@ val KotlinType?.toClassDescriptor: ClassDescriptor?
     }
 
 val ClassDescriptor.shouldHaveGeneratedMethodsInCompanion: Boolean
-    get() = this.isSerializableObject || this.isSerializableEnum() || (this.kind == ClassKind.CLASS && hasSerializableOrMetaAnnotation) || this.isSealedSerializableInterface
+    get() = this.isSerializableObject
+            || this.isSerializableEnum()
+            || (this.kind == ClassKind.CLASS && hasSerializableOrMetaAnnotation)
+            || this.isSealedSerializableInterface
+            || this.isSerializableInterfaceWithCustom
 
 val ClassDescriptor.isSerializableObject: Boolean
     get() = kind == ClassKind.OBJECT && hasSerializableOrMetaAnnotation
@@ -124,6 +128,9 @@ val ClassDescriptor.isInternallySerializableObject: Boolean
 val ClassDescriptor.isSealedSerializableInterface: Boolean
     get() = kind == ClassKind.INTERFACE && modality == Modality.SEALED && hasSerializableOrMetaAnnotation
 
+val ClassDescriptor.isSerializableInterfaceWithCustom: Boolean
+    get() = kind == ClassKind.INTERFACE && hasSerializableAnnotationWithArgs
+
 val ClassDescriptor.isAbstractOrSealedOrInterface: Boolean
     get() = kind == ClassKind.INTERFACE || modality == Modality.SEALED || modality == Modality.ABSTRACT
 
@@ -196,6 +203,15 @@ private val ClassDescriptor.hasSerializableAnnotationWithoutArgs: Boolean
         return psi.valueArguments.isEmpty()
     }
 
+private val ClassDescriptor.hasSerializableAnnotationWithArgs: Boolean
+    get() {
+        if (!hasSerializableAnnotation) return false
+        // If provided descriptor is lazy, carefully look at psi in order not to trigger full resolve which may be recursive.
+        // Otherwise, this descriptor is deserialized from another module, and it is OK to check value right away.
+        val psi = findSerializableAnnotationDeclaration() ?: return (serializableWith != null)
+        return psi.valueArguments.isNotEmpty()
+    }
+
 private fun Annotated.findSerializableAnnotationDeclaration(): KtAnnotationEntry? {
     val lazyDesc = annotations.findAnnotation(serializableAnnotationFqName) as? LazyAnnotationDescriptor
     return lazyDesc?.annotationEntry
@@ -277,6 +293,7 @@ fun ClassDescriptor.needSerializerFactory(): Boolean {
     if (serializableClass.isSerializableEnum()) return true
     if (serializableClass.isAbstractOrSealedSerializableClass()) return true
     if (serializableClass.isSealedSerializableInterface) return true
+    if (serializableClass.isSerializableInterfaceWithCustom) return true
     if (serializableClass.declaredTypeParameters.isEmpty()) return false
     return true
 }