Stronger typed resource tracker about wgpu

[kvark]

Experimented with this quite a bit in kvark@d46b0dd , and it's hell of a complex thing to lift to a type level. Basically, there are many use cases, and we are still in heavy development phase. It appears to me that we should let it crystallize a bit more before trying to typify it.

The basic idea was to introduce a trait State that would differentiate between the trackers that only care about the current state versus ones that care both about the initialization and the current state:

#[derive(Clone)]
struct Track<S> {
    ref_count: RefCount,
    state: S,
    epoch: Epoch,
}

trait State<U> {
    fn new(usage: U) -> Self;
    fn init(&self) -> U;
    fn last(&self) -> U;
    fn set(&mut self, usage: U) -> U;
}

impl<U: Copy> State<U> for U {} // current-state tracking
impl<U: Copy> State<U> for Range<U> {} // init + current state tracking

The difficulties I faced is - implementing the consume* logic for various combinations of source/destination, then insert_barriers needing to be generic somehow.

[kvark]

There's been a ton of work and rework done for the resource tracker. I don't think the issue is actual any more.