Revert #2425

[marc0246]

This reverts #2425. I was cooking something, but plans have changed and we're going with a new crate for the new command buffer and deprecating the old one, so it doesn't make sense to break code for no reason now.

Changelog:
Remove these lines:

### Breaking changes
Changes to command buffers:
- Merged `{Primary,Secondary}AutoCommandBuffer` into `CommandBuffer` and the corresponding `RecordingCommandBuffer::{primary,secondary}` into `new`.
- `RecordingCommandBuffer` no longer has a type parameter for the command buffer level.

[Rua]

Should RecordingCommandBuffer not be renamed back to AutoCommandBufferBuilder as well?

[marc0246]

Does it have to be in this PR? This PR is reverting #2425.

[Rua]

No, I just wasn't sure if you were planning to do them in stages.