Add basic Adapter blocklist

Adds a basic adapter blocklist and adds two cases to it.

By default, the blocklist is disabled until Chromium can enable it
explicitly - perhaps based on --enable-unsafe-webgpu or some other
flag. It will be switched to default to true in the future.

about://gpu would disable the blocklist so all the adapters are
visible there, but WebGPU would enable it. Trusted users of Dawn
that are aware of potential bugs may also disable it.
One downside is that about://gpu won't surface directly that an
adapter is on the system, but blocklisted for WebGPU. Something
like that can be added in the future, if necessary.

In the future, this should probably be merged with Chromium's
software_rendering_list.json, but that list doesn't support
multi-adapter systems well (for blocklisting just one adapter),
and it doesn't understand all the information we need for the
current blocklist.

Bug: dawn:1254, dawn:1196, tint:1753
Change-Id: I992bcd10dd5d3f5b23319fc4ec699b06bb1117da
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/119061
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>

include/dawn/native/DawnNative.h

@@ -181,6 +181,9 @@ class DAWN_NATIVE_EXPORT Instance {
     // Enable debug capture on Dawn startup
     void EnableBeginCaptureOnStartup(bool beginCaptureOnStartup);
 
+    // Enable / disable the adapter blocklist.
+    void EnableAdapterBlocklist(bool enable);
+
     // TODO(dawn:1374) Deprecate this once it is passed via the descriptor.
     void SetPlatform(dawn::platform::Platform* platform);