To use custom annotation it requires the type to be equality_comparable

[bruce-webb]

*Issue number of the reported bug or feature request: p3394 usage

Describe your changes
When using a custom annotations and getting access to it with the function annotation_of_type the T is required to be equality_comparable.

If not the compile error message leads down to missing operator != for the type

Testing performed
When testing with new annotations types clangd reports that T doesn't meet the requires clauses. The compile message is also cleaner as well.

namespace lua {
struct rename {
  const char *name;
  
  auto operator<=>(const rename &) const = default;
};

struct Person
{
  [[=lua::rename("firstName")]] std::string first_name;
};

template<typename T>
consteval auto GetName() -> std::string_view {
    return
        std::meta::annotation_of_type<lua::rename>(^^T)
            .transform([](lua::rename rename) {
              return std::string_view(rename.name);
            })
            .value_or(std::meta::display_string_of(^^T));
}