Refactor SkiaVkRenderEngine's VulkanInterface and DestroySemaphoreInfo

... to be shareable (and more defensive).

VulkanInterface is mostly unmodified, other than being converted from a
struct to a class. Part of that entails adding getters for a few fields.

DestroySemaphoreInfo now handles its own destruction, and supports
owning N VkSemaphores (required for Graphite). It also now stores which
VulkanInterface it needs to be destroyed with, so that the callback path
no longer needs to reference a static VulkanInterface (one tiny step
towards b/300533018.)

Also incidentally fixed a bug where realtime priority status may have
been left uninitialized.

Bug: b/293371537
Test: manual testing + existing tests transitively exercise these classes
Change-Id: I3a7782d76c72b9ad61f3a1d6968c352a86a2af9f