[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/dataFlow/IsExpression.fir.kt

@@ -2,5 +2,5 @@ fun f(a: Boolean, b: Int) {}
 
 fun foo(a: Any) {
     <!INAPPLICABLE_CANDIDATE!>f<!>(a is Int, a)
-    1 <!INAPPLICABLE_CANDIDATE!>+<!> a
-}
+    1 <!NONE_APPLICABLE!>+<!> a
+}