[IR][tests] New test: non-abstract callable member in abstract class becomes abstract

^KT-53663

compiler/testData/klibABI/nonAbstractFunctionInInterfaceBecomesAbstract/lib2/l2.kt

@@ -0,0 +1,15 @@
+package lib2
+
+import lib1.A
+
+class B : A {
+    override fun bar() = -42
+
+    val unlinkedFunctionUsage get() = foo()
+}
+
+class B1 : A {
+    override fun bar() = -42
+
+    val unlinkedFunctionUsage = foo() // Expected failure on class instance initialization.
+}

compiler/testData/klibABI/nonAbstractFunctionInInterfaceBecomesAbstract/lib2/module.info

@@ -0,0 +1,2 @@
+STEP 0:
+    dependencies: stdlib, lib1