Changing array to be an associative array so that the Name function can work with non-sequential enums as well as those beginning at something other than zero. (#5151)

Also including the resulting changes in php files.

src/idl_gen_php.cpp

@@ -828,7 +828,7 @@ class PhpGenerator : public BaseGenerator {
     for (auto it = enum_def.vals.vec.begin(); it != enum_def.vals.vec.end();
          ++it) {
       auto &ev = **it;
-      code += Indent + Indent + "\"" + ev.name + "\",\n";
+      code += Indent + Indent + enum_def.name + "::" + ev.name + "=>" + "\"" + ev.name + "\",\n";
     }
 
     code += Indent + ");\n\n";