add slides from siggraph '22

Add experiments folder

update README.md

added tests and related scaffolding required for CI and submission to package registry, fixed CI validation errors, bump version to 0.19.0-preview.1, update CHANGELOG.md

bump version to 0.18.3-exp.1, update CHANGELOG.md

update CHANGELOG.md

guard against division by zero in angular damping

fix a few issues preventing builds for some platforms (avoid use of vector logical operations in volume trace, guard against volume transfer functions being declared for non-writable targets, guard against vr module not present before checking single pass instanced stereo)

reduce num. shader variants produced by HairVertex (limit procedural keyword to vertex stage), fix shader warnings when building for XR, fix an issue with indirect instanced on 2020.x

add workaround for crash affecting builds (resolves #107, thanks @schemaxxx!)

bump version to 0.18.2-exp.1, update CHANGELOG.md

Update hair sample prefab, remove attachment script as it's not present unless Digital Human Package is included in the project

bump version to 0.18.1-exp.1, update CHANGELOG.md

fix missing defaults

bump version to 0.18.0-exp.1, update CHANGELOG.md