[FIR] Improve diagnostic reporting & don't use error symbol for candidate if possible

Also introduce few new diagnostics:
- NONE_APPLICABLE more many inapplicable candidates
- HIDDEN for visible candidates

compiler/testData/diagnostics/tests/controlStructures/forLoopWithNullableRange.fir.kt

@@ -8,9 +8,9 @@ class It {
 }
 
 fun test(c: Coll?) {
-  <!INAPPLICABLE_CANDIDATE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (x in c) {}<!>
+  <!INAPPLICABLE_CANDIDATE!>for (x in c) {}<!>
 
   if (c != null) {
     for(x in c) {}
   }
-}
+}