[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/scopes/protectedVisibility/innerProtectedClass.fir.kt

@@ -8,6 +8,6 @@ class Foo : BaseClass() {
     fun bar() {
         val f = foo()
         f.x
-        f.<!INAPPLICABLE_CANDIDATE!>y<!>
+        f.<!HIDDEN!>y<!>
     }
 }