This commit alters the expansion order of custom macros-1.1 style `#[derive]`
modes. Instead of left-to-right the expansion now happens in three categories,
each of which is internally left-to-right:
* Old-style custom derive (`#[derive_Foo]`) is expanded
* New-style custom derive (macros 1.1) is expanded
* Built in derive modes are expanded
This gives built in derive modes maximal knowledge about the struct that's being
expanded and also avoids pesky issues like exposing `#[structural_match]` or
`#[rustc_copy_clone_marker]`.
cc #35900
e5e7021ca5