[JVM_IR] Generate line numbers and nops for init blocks.

This seems to be what JVM does and it allows you to set a
breakpoint on the init line.

compiler/testData/debug/stepping/initBlocksCompanion.kt

@@ -0,0 +1,52 @@
+// FILE: test.kt
+
+class A {
+    companion object {
+        val s: String
+
+        init {
+            s = "OK"
+        }
+
+        val x = x()
+
+        init { val a = 32 }
+
+        init {
+            val b = 42
+        }
+
+        init
+        {
+            val c = 43
+        }
+    }
+}
+
+fun x() = ""
+
+fun box() {
+    A.x
+    A.s
+}
+
+// JVM backend has extra steps for getX and getS.
+
+// TODO: since these tests operate as step-into, we do not get any steps
+// in the <clinit> for the companion object. Maybe extend the test infrastructure
+// with directives to set break points in order to test this.
+
+// LINENUMBERS
+// test.kt:29 box
+// test.kt:11 getX
+// LINENUMBERS JVM
+// test.kt:11 getX
+// LINENUMBERS
+// test.kt:29 box
+// test.kt:30 box
+// test.kt:5 getS
+// LINENUMBERS JVM
+// test.kt:5 getS
+// LINENUMBERS
+// test.kt:30 box
+// test.kt:31 box