Zygote: preload Vulkan driver if hwui renders with Vulkan

In Android 12, vkEnumerateInstanceVersion is made to trigger driver
loading and the api itself neither has extra overhead nor talk to the
driver. So this change uses vkEnumerateInstanceVersion to preload
Vulkan driver in Zygote.

Bug: 135536511
Test: atest CtsUiRenderingTestCases all pass on GL backend
Test: atest CtsUiRenderingTestCases no regression on VK backend
Change-Id: I5017b922843aadc2c4a4237711b8011857703129