[native][d3d12] Fix ShaderVisibleDescriptorAllocator failing to handle large resource table size jumps

The ShaderVisibleDescriptorAllocator was designed to handle BindGroups
that are limited to how many resources can be bound per group per draw
(kMaxBindingsPerBindGroup = 1000). As such, it starts with a min heap
size of 4096 descriptors (for views) and doubles it when needing to
realloc.

ResourceTables, however, are much larger, limited currently to
kMaxResourceTableSize (64K), so growing a table by more than double the
current heap size in ShaderVisibleDescriptorAllocator would fail
(assert).

This CL reworks ShaderVisibleDescriptorAllocator to no longer
automatically grow its heap, but rather now takes in a
'minDescriptorCount' so that it can resize its heap to fit. It still
pools allocations once it reaches the max size. With this, we now
compute the total number of view and sampler descriptors required during
draw/dispatch and use this to resize the heaps.

Bug: 496379067
Change-Id: I67ade6cdf29802827835f08dcd57876a927cc2cd
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/299595
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>