FIR checker: report UNSAFE_CALL for overloaded function calls

Previously if an unsafe call is to an overloaded function, FIR checkers
report NONE_APPLICABLE. This change instead report them as UNSAFE_CALL
or its variants.

compiler/testData/diagnostics/tests/smartCasts/objectLiterals/exclexcl.fir.kt

@@ -16,7 +16,7 @@ fun foo(): Int {
         k.run()
         val d: Int = c
         // a is not null because of k constructor, but we do not know it
-        return a <!NONE_APPLICABLE!>+<!> d
+        return a <!UNSAFE_OPERATOR_CALL!>+<!> d
     }
     else return -1
 }

compiler/testData/diagnostics/tests/smartCasts/objectLiterals/exclexclArgument.fir.kt

@@ -11,7 +11,7 @@ fun foo(): Int {
         }
         k.run()
         val d: Int = c
-        return a <!NONE_APPLICABLE!>+<!> d
+        return a <!UNSAFE_OPERATOR_CALL!>+<!> d
     }
     else return -1
 }

compiler/testData/diagnostics/tests/smartCasts/objectLiterals/exclexclTwoArgument.fir.kt

@@ -15,7 +15,7 @@ fun foo(): Int {
         }
         k.run()
         val d: Int = c
-        return a <!NONE_APPLICABLE!>+<!> d
+        return a <!UNSAFE_OPERATOR_CALL!>+<!> d
     }
     else return -1
 }