FIR checker: skip error named reference if receiver is unresolved

Currently, FIR reports errors caused by previous resolution failure. For
example with unresolved `a` and `b` in code `a.b`, both `a` and `b` are
highlighted. FE1.0 only highlights `a` since it's the root cause. This
change applies this heuristics when reporting FirDiagnostics.

compiler/testData/diagnostics/tests/incompleteCode/unresolvedOperation.fir.kt

@@ -1,4 +1,4 @@
 fun foo(a: Int) {
-    <!UNRESOLVED_REFERENCE!>!<!><!UNRESOLVED_REFERENCE!>bbb<!>
+    !<!UNRESOLVED_REFERENCE!>bbb<!>
     <!UNRESOLVED_REFERENCE!>bbb<!> + a
-}
+}