Vulkan: Port renderer to Fuchsia

Add DisplayVk and WindowSurfaceVk subclasses for Fuchsia to the vulkan
renderer, as well as an implementation of OSWindow that renders
fullscreen for the test suite.

Disallow use of the vulkan loader from third_party as Fuchsia uses a fork
of the loader and has not sent those changes upstream yet.

Add a small wayland-inspired library libfuchsia-egl to provide a type
"struct fuchsia_egl_window" to use as EGLNativeWindowType. This type
combines a zx_handle_t to an image pipe channel and a surface size.

Image pipes can only be used once to create a VkSurfaceKHR. This means we
have to recreate the pipe in tests that call eglCreateWindowSurface more
than once with a single OSWindow, or the second call will fail. Add a
resetNativeWindow() method to accomplish this.

BUG=angleproject:2475
TEST=angle_end2end_tests on Fuchsia

Change-Id: I71a613a362dd1c8aada49a3c02ae461e064457bf
Reviewed-on: https://chromium-review.googlesource.com/c/1446496
Commit-Queue: Michael Spang <spang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>

util/android/AndroidWindow.cpp

@@ -31,6 +31,8 @@ bool AndroidWindow::initialize(const std::string &name, size_t width, size_t hei
 }
 void AndroidWindow::destroy() {}
 
+void AndroidWindow::resetNativeWindow() {}
+
 EGLNativeWindowType AndroidWindow::getNativeWindow() const
 {
     // Return the entire Activity Surface for now