This extension allows the viewport's minimum and maximum depth to be
outside of the 0.0 to 1.0 range:
https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_depth_range_unrestricted.html

Note that while most extensions don't change the behavior of the logical
device whether they're enabled or not (since they just allow new calls,
enums, or values which are otherwise undefined behavior and implementing
the functionality of the extension is valid as "undefined" behavior),
enabling/disabling this extension does cause an observable difference.

Bug: b/163135814
Tests: dEQP-VK.*depth_range_unrestricted*
Change-Id: I418a2e7226140719af08601d8919f4cdbc7a237c
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/47608
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>