[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/incompleteCode/kt2014.fir.kt

@@ -14,7 +14,7 @@ fun x(f : Foo) {
 
     f.<!UNRESOLVED_REFERENCE!>a<!>()
     <!UNRESOLVED_REFERENCE!>c<!>()
-    <!INAPPLICABLE_CANDIDATE!>R<!>()
+    <!HIDDEN!>R<!>()
 }
 
-object R {}
+object R {}