KT-37986 Force boxing of inline class returned from function reference

KT-37998 Provide KotlinType for safe call

compiler/testData/codegen/box/inlineClasses/kt37998.kt

@@ -0,0 +1,13 @@
+inline class Z(val x: Int)
+
+class A {
+    fun foo() = Z(42)
+}
+
+fun test(a: A?) = a?.foo()!!
+
+fun box(): String {
+    val t = test(A())
+    if (t.x != 42) throw AssertionError("$t")
+    return "OK"
+}