Improve compile-time opti in options_tools.h.in

[mwestphal]

Is your feature request related to a problem? Please describe. With the merge of https://github.com/f3d-app/f3d/pull/1471, there are potential compile time optimisation that have not been implemented, let try to improve that.

eg:

constexpr std::array<std::string_view> getNames()
{
  std::array<std::string_view> vec{ ${_options_lister} };
  return vec;
}