* Replace &[T] in descriptor structs with Cow<[T]>
* Changed label fields to use Cow<'a, str>
* Deduplicate types across the tracing API
Introduce the ToStatic trait
* Deduplicate trace::RenderBundleDescriptor
* Remove ugly ToOwned bounds
* Simplifiy Action variants
* Make Clone bounds on type defs less verbose
* Fix a error in play.rs
* Remove ToStatic, and Make Action<'a> borrow descriptors instead
