Added visibility bitmask as an alternative SSAO method

[dragostis]

Early implementation. I still have to fix the documentation and consider writing a small migration guide.

Questions left to answer:

• should thickness be an overridable constant?
• is there a better way to implement Eq/Hash for SSAOMethod?
• do we want to keep the linear sampler for the depth texture?
• is there a better way to separate the logic than preprocessor macros?

[github-actions]

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[JMS55]

References for reviewers:

• https://ar5iv.labs.arxiv.org/html/2301.11376
• https://cdrinmatane.github.io/posts/ssaovb-code

[dragostis]

I added a few questions to answer before merging this and also added a linear sampler for the depth texture since I noticed it slightly improves some of the ghosting noticeable in small objects that happens due to the low resolution mip that gets selected for far-away samples.