Use DEPS to pull in VulkanMemoryAllocator.

Also updated the gn_to_bp.py to handle using the DEPSed vk_mem_alloc.h.
When rolled into Android we will copy the vk_mem_alloc.h from a local
DEPS checkout into a vma_android folder that will be checked into the
skia that lands with Android. We are using vma_android folder instead
of the current third_party/vulkanmemoryallocator folder because we
soon plan to move the latter into src/ instead of third_party. So just
using a different directory allows us to avoid doing an additional
change to the auto roller.

Bug: skia:13240
Bug: skia:13242
Change-Id: Ia344e13e3f7c7efecc2e6a97a96820f3ae58b5c2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/531318
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Ravi Mistry <rmistry@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
6 files changed