Add validations on `clip_distances` and maximum inter-stage location

This patch adds the validation on the use of `clip_distances` and
the maximum location of the inter-stage shader variables according
to the latest WebGPU SPEC.

`clip_distances` will not only consume inter-stage shader variable
slots, but also consume the maximum location of inter-stage shader
variables, which is required by Vulkan. According to the Vulkan
validation layer, the total number of inter-stage shader components
is computed by the maximum location of all the inter-stage shader
variables, so we should reserve the locations for `clip_distances`.

For example, suppose the maximum location of the vertex outputs is
30, and there is builtin position (4) and clip_distances with size
1, so the Vulkan validation layer thinks the total vertex shader
output components is 129 (31 * 4 + 4 + 1) which is over the maximum
number of the total vertex shader output components on Intel GPUs.

Bug: 358408571
Test: dawn_unittests, dawn_end2end_tests
Change-Id: If89cb10b63011dd34df71389411072b4a5cc5d18
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/206354
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Kai Ninomiya <kainino@chromium.org>