Vulkan: External image layout needs to be ReadWrite

Textures specified through external images need to
transition to a ReadWrite layout and not ReadOnly.

Bug: angleproject:4791
Change-Id: I8c0d5999d65499de6a36725ed1cc9c390c479c8c
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2270513
Commit-Queue: Mohan Maiya <m.maiya@samsung.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>

src/libANGLE/renderer/vulkan/TextureVk.cpp

@@ -1072,7 +1072,7 @@ angle::Result TextureVk::setEGLImageTarget(const gl::Context *context,
         vk::CommandBuffer *commandBuffer = nullptr;
         ANGLE_TRY(contextVk->endRenderPassAndGetCommandBuffer(&commandBuffer));
         mImage->changeLayoutAndQueue(VK_IMAGE_ASPECT_COLOR_BIT,
-                                     vk::ImageLayout::AllGraphicsShadersReadOnly,
+                                     vk::ImageLayout::AllGraphicsShadersReadWrite,
                                      rendererQueueFamilyIndex, commandBuffer);
     }