Vulkan: Dynamically grow descriptor pool sizes Initial testing using benchmarks shows that the majority of the descriptor pools allocate fewer than 32 descriptor sets worth of descriptors. This CL reduces the initial size of each pool from 128 to 32 to reduce memory consumption. Additionally, when a pool is exhausted and a new one is created, the size of the pool doubles each time, up to a max of 512 descriptor sets worth of descriptors. This allows us to aggressively increase the size of the pools that appear to be very hot and decrease the total number of pools created. Bug: angleproject:5067 Test: CQ Change-Id: I190059cf04134902d6251d475dd908c1cbb82b58 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2430193 Reviewed-by: Charlie Lao <cclao@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Tim Van Patten <timvp@google.com>