WIP: Feature multiview

[Limeth]

Once finished, Fixes #3303. Hopefully the API usage is correct. An example demonstrating the Multiview feature would be desirable. Feedback is appreciated.

PR checklist:

• [x] make succeeds (on *nix)
• [ ] make reftests succeeds
• [ ] tested examples with the following backends:
• [ ] rustfmt run on changed code

[Limeth]

The @monocodus bot seems to have been recommending odd style changes, such as incorrect indentation, so I did not apply their suggestions this time. I have tried creating a Multiview example derived from the quad example, but I got stuck when implementing the synchronization logic, as I do not feel confident in my understanding of it and how it is structured in gfx.

[kvark]

@Limeth we can deal with monocodus later. The synchronization model is exactly what Vulkan has.

[pavel-ignatovich]

@Limeth Hey, I noticed you're having some problem with monocodus. I've tried to run rustfmt locally on a given code to figure out which part of the suggestion is wrong but it seems like it gives the same result as listed in the suggestion. Could you please point out the wrong indentation in the suggestion?

Also please feel free to use our issue tracker to describe what exactly is wrong, so that our team can resolve the issue in a timely manner.

[Limeth]

@P-ignatovich Please see the suggested changes I approved previously: https://github.com/gfx-rs/gfx/pull/3323/commits/2bfbd4d4efaa4bc127e8392f679cf51cfc2e2c43

[pavel-ignatovich]

@Limeth Thank you for your answer! I took a closer look at these changes and found the issues you mentioned. They're caused by incorrect processing of huge formatting fixes by monocodus. We'll see what we can do about it.

For now, I've disabled rustfmt in out default config so users don't get confused with its behavior.

Thank you very much for your report! Hope we'll make it work better soon :)

[kvark]

@Limeth are you going to come back to this PR?

[Limeth]

I would like to, but I've been hesitant because there's some kind of UB making it crash on the example, and I couldn't figure out what it was caused by.