[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/VisibilityInClassObject.fir.kt

@@ -19,15 +19,15 @@ open class A {
 fun fromOutside() {
     devNull(A.internal_val)
     devNull(A.public_val)
-    devNull(A.<!INAPPLICABLE_CANDIDATE!>private_val<!>)
-    devNull(A.<!INAPPLICABLE_CANDIDATE!>protected_val<!>)
+    devNull(A.<!HIDDEN!>private_val<!>)
+    devNull(A.<!HIDDEN!>protected_val<!>)
 }
 
 class B: A() {
     fun fromSubclass() {
         devNull(A.internal_val)
         devNull(A.public_val)
-        devNull(A.<!INAPPLICABLE_CANDIDATE!>private_val<!>)
+        devNull(A.<!HIDDEN!>private_val<!>)
         devNull(A.protected_val)
     }
 }