[IR][tests] Add tests for removal-of-abstract-fun IR linkage case

^KT-50771

compiler/testData/klibABI/removeAbstractFunctionFromAbstractClass/main/m.kt

@@ -0,0 +1,19 @@
+import lib1.A
+import lib2.B
+
+fun box(): String {
+    val a: A = B()
+
+    try {
+        val answer: Int = a.foo() // <-- should throw linkage error here
+        println(answer)
+    } catch (e: Throwable) {
+        if (e.isLinkageError("lib2.B.foo")) return "OK"
+    }
+
+    return "FAIL"
+}
+
+private fun Throwable.isLinkageError(symbolName: String): Boolean =
+    this::class.simpleName == "IrLinkageError"
+            && message == "Abstract function $symbolName is not implemented in non-abstract class ${symbolName.substringBeforeLast(".")}"

compiler/testData/klibABI/removeAbstractFunctionFromAbstractClass/main/module.info

@@ -0,0 +1,2 @@
+STEP 0:
+    dependencies: stdlib, lib1, lib2