[FIR] Don't create backing field for property without explicit type

#KT-41977 Fixed

compiler/fir/analysis-tests/testData/resolve/properties/noBackingFieldInProperty.kt

@@ -0,0 +1,15 @@
+// ISSUE: KT-41977
+
+class A {
+    val field: String = "" // (1)
+
+    val x
+        get() = field.length // should be ok, resolve to (1)
+}
+
+class B {
+    val field: String = ""
+
+    val x: Int
+        get() = field.<!UNRESOLVED_REFERENCE!>length<!> // should be an error
+}