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/fir/analysis-tests/testData/resolve/expresssions/nestedObjects.kt

@@ -6,5 +6,5 @@ object A {
 
 object B
 
-val err = B.<!UNRESOLVED_REFERENCE!>A<!>.<!UNRESOLVED_REFERENCE!>B<!>
+val err = B.<!UNRESOLVED_REFERENCE!>A<!>.B
 val correct = A.B.A