On Windows placing the vulkan-1.dll next to the executables suffices for
them to load SwiftShader instead of the system's Vulkan ICD loader (if
present).

Also make warnings-as-errors only affect our own projects, and put
things into project folders.

Bug: b/141361933
Change-Id: Ibdf8bcb992aa484d4bebaaf52ae77a8ced61709a
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/40788
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>