[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/PrivateFromOuterPackage.fir.kt

@@ -10,8 +10,8 @@ package outer.p1
 import outer.a
 
 fun use() {
-    <!INAPPLICABLE_CANDIDATE!>a<!>()
-    outer.<!INAPPLICABLE_CANDIDATE!>B<!>()
+    <!HIDDEN!>a<!>()
+    outer.<!HIDDEN!>B<!>()
 }
 
 // FILE: c.kt
@@ -20,6 +20,6 @@ package outer.p1.p2
 import outer.a
 
 fun use() {
-    <!INAPPLICABLE_CANDIDATE!>a<!>()
-    outer.<!INAPPLICABLE_CANDIDATE!>B<!>()
-}
+    <!HIDDEN!>a<!>()
+    outer.<!HIDDEN!>B<!>()
+}