Task graph [5/10]: the new command buffer

[marc0246]

Follow up to #2560, implementing the new command buffer.

This is a copy of the old command buffer, the only difference is that this command buffer accepts Id<Resource>s rather than Arc<Resource>s and takes everything in by reference. I converted the rest of vulkano-taskgraph to take borrowed values as well. This is a first step towards eradicating owned collections in vulkano's public API.

I added a bloom example because it's a very good demonstration of the task graph:

• It uses a task graph with multiple tasks, some doing graphics and some doing compute.
• It does subresource accesses.
• The bloom task does manual pipeline barriers.