Ensure that the replace() SQL function always returns a TEXT value even

when its first argument is numeric and its second argument is an empty string.
Fix for the issue reported by
[forum:/forumpost/3776b48e71|forum post 3776b48e71].

FossilOrigin-Name: 01868ebcd25fadb2034da234c0636e82d07c5abc902ef66493cadfc988e74d7b

test/func.test

@@ -1042,6 +1042,9 @@ do_test func-21.8 {
     SELECT replace('aaaaaaa', 'a', '0123456789');
   }
 } {0123456789012345678901234567890123456789012345678901234567890123456789}
+do_execsql_test func-21.9 {
+  SELECT typeof(replace(1,'',0));
+} {text}
 
 ifcapable tclvar {
   do_test func-21.9 {