Implement rkyv endianess

[MucTepDayH16]

I've notice, that you are using NotNan<T>/OrderedFloat<T> as Archived values. This leads to compilation failure if rkyv used with archive_le or archive_be features:

cargo t -F rkyv/archive_le

error[E0308]: mismatched types
    --> src/lib.rs:2013:46
     |
2013 |         let deser_float: OrderedFloat<f64> = archived_value.deserialize(&mut deserializer).unwrap();
     |                          -----------------   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `OrderedFloat<f64>`, found `With<_, _>`
     |                          |
     |                          expected due to this
     |
     = note: expected struct `OrderedFloat<f64>`
                found struct `With<_, _>`

My PR implements rkyv::Archive properly considering this features

[mbrubeck]

Thank you!