FIR deserializer: add proper container class id to nested class members

compiler/fir/resolve/testData/resolve/stdlib/companionLoad.kt

@@ -0,0 +1,3 @@
+fun main() {
+    val y = Int.MAX_VALUE
+}

compiler/fir/resolve/testData/resolve/stdlib/companionLoad.txt

@@ -0,0 +1,4 @@
+FILE: companionLoad.kt
+    public final fun main(): R|kotlin/Unit| {
+        lval y: R|kotlin/Int| = R|kotlin/Int|.R|kotlin/Int.Companion.MAX_VALUE|
+    }