Access Delta concept. New algorithm of resource synchronization inside one command buffer

[AndrewB330]

This is the first part of an effort to improve resource synchronization in vulkano. Original issue and design proposal: #1914
In the design proposal I added a new section "Step 1. Introduction of Access Delta concept" that briefly describes this new concept .

1. Added implementation of Access Delta for image and buffer resources
2. Added append_command method and added it to all places where we are adding a command.
3. Replaced old way of handling command buffer synchronization with a new access delta concept.

This change should not change an overall behavior but also introduces a few improvements: now we don't need to check for a conflicts because we can now resolve all of them, now we can build more optimal barriers and in future this will help us to add a synchronization between command buffers.

TODO: There are still a few todos in this PR that I will resolve in following commits.

Right now this PR is split into 3 commits for easier code review.