[FIR] Add CFG nodes, add multiple subGraphs for CFGOwner

compiler/fir/analysis-tests/testData/resolveWithStdlib/initialization/fromLocalMembers.kt

@@ -0,0 +1,46 @@
+fun test1() {
+    val x: Int
+
+    fun func() {
+        x = 0
+    }
+
+    println(<!UNINITIALIZED_VARIABLE!>x<!>)
+}
+
+
+fun test2() {
+    val x: Int
+    val y: Int
+
+    object {
+        init {
+            x = 0
+        }
+
+        fun localFunc() {
+            y = 0
+        }
+    }
+
+    println(<!UNINITIALIZED_VARIABLE!>x<!>)
+    println(<!UNINITIALIZED_VARIABLE!>x<!>)
+}
+
+fun test3() {
+    val x: Int
+    val y: Int
+
+    class A {
+        init {
+            x = 0
+        }
+
+        fun localFunc() {
+            y = 0
+        }
+    }
+
+    println(<!UNINITIALIZED_VARIABLE!>x<!>)
+    println(<!UNINITIALIZED_VARIABLE!>x<!>)
+}