RE-SkiaVk: Ref-count semaphores to prevent premature deletion

The lower-level parts of SkiaVk occassionally deletes a semaphore
still being used by SkiaVkRenderEngine.  This fixes that by
ref-counting the SkiaVkRenderEngine-created semaphores.

Test: Logcat with a HWASAN build
Bug: 274419744
Bug: 270287296
Change-Id: I05cecff69b4712daa4d7b52eb84c0027491369f5