Support fun interfaces in kotlinx-metadata

#KT-37421 Fixed

compiler/fir/analysis-tests/testData/loadCompiledKotlin/class/FunInterface.txt

@@ -0,0 +1,4 @@
+public abstract interface F : R|kotlin/Any| {
+    public abstract fun R|kotlin/String|.f(x: R|kotlin/Int|): R|kotlin/Unit|
+
+}

compiler/fir/analysis-tests/tests/org/jetbrains/kotlin/fir/FirLoadCompiledKotlinGenerated.java

@@ -604,6 +604,11 @@ public class FirLoadCompiledKotlinGenerated extends AbstractFirLoadCompiledKotli
             runTest("compiler/testData/loadJava/compiledKotlin/class/EnumWithPrimitiveConstructorParameter.kt");
         }
 
+        @TestMetadata("FunInterface.kt")
+        public void testFunInterface() throws Exception {
+            runTest("compiler/testData/loadJava/compiledKotlin/class/FunInterface.kt");
+        }
+
         @TestMetadata("InheritClassSimple.kt")
         public void testInheritClassSimple() throws Exception {
             runTest("compiler/testData/loadJava/compiledKotlin/class/InheritClassSimple.kt");