Non-borrowing rust bindings

[kvark]

Related to #37 , also commentary from @omni-viral

Our current Rust bindings assume unique ownership over the IDs. This is idiomatic but sometimes inconvenient for the clients that need more freedom. Since our native layer is safe, we can have the IDs copyable on the Rust level as well, it's just going to be slightly different kind of API.

It would be nice not to fragment the community with another Rust wrapper. Perhaps, we can just control it by a feature? I.e.

#[cfg_attr(feature = "copy", derive(Clone, Copy))]
struct Buffer {
  id: BufferId,
}

impl<'a> RenderPassEncoder<'a> {
  #[cfg(feature = "copy")]
  pub fn end_pass(self) { ...
  }
}

[zakarumych]

It would be surprising for user that assume unique ownership to find out copies of his resources because another crate in dependency graph enabled that feature.

[kvark]

@omni-viral good point (although, again, it's not critical - it's not making the library unsafe). We should make it so that situation is impossible. The point of providing a feature here is not to allow different clients to enabled or disable it, but to keep the same code base.

[zakarumych]

I see what you mean. But this means user can't rely on uniqueness of the resource id if he gives a reference to it somewhere.
In this case I can't see any reason to have it under feature gate.

[cwfitzgerald]

Superseded by #1453.