[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/inference/completeInferenceIfManyFailed.fir.kt

@@ -12,6 +12,6 @@ fun <T: Any> joinT(x: Comparable<*>, y: T): T? {
 }
 
 fun test() {
-    val x2 = <!INAPPLICABLE_CANDIDATE!>joinT<!>(Unit, "2")
+    val x2 = <!NONE_APPLICABLE!>joinT<!>(Unit, "2")
     <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><String?>(x2)
-}
+}