fix and refactor vulkan constant and storage buffer mapping

[DavidLokison]

No description provided.

[DavidLokison]

Reasoning behind the refactoring part of the shader class was to get both constant and storage buffer calculations in a similar shape. I also noticed some consistencies in the other buffers as well, which was the baseline for the idea to add some functions for code that appears the same every time.

So I basically prepared such a change but didn't add too many functions at once now since that would require some more thought.

Also the usage of bindingLayout.binding and block->binding seemed to be somewhat arbitrary. Since they "should" point to the same value it shouldn't be an issue in the long run but I have set them all to block->binding to make it clear that this is indeed the same value.

[Duttenheim]

Looks good, greatly simplified this mess! 👍

[DavidLokison]

Have rebased the PR to the master as merging was reverting some changes I made which would duplicate some logic. It's good to merge in my opinion.