[tools]: Generate intrinisic test cases

Add test/intrinsics/intrinsics.wgsl.tmpl that generates a vast set of intrinsic overload permutations into test/intrinsics/gen/...

Add expected output for all of these, including 'SKIP' headers for those that currently fail.

Fixed: tint:832
Change-Id: Id6888df52c07f35e7a55199f2ad4d842c6e2595c
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/53051
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>
diff --git a/test/intrinsics/gen/dpdx/0763f7.wgsl.expected.msl b/test/intrinsics/gen/dpdx/0763f7.wgsl.expected.msl
new file mode 100644
index 0000000..082d924
--- /dev/null
+++ b/test/intrinsics/gen/dpdx/0763f7.wgsl.expected.msl
@@ -0,0 +1,12 @@
+#include <metal_stdlib>
+
+using namespace metal;
+void dpdx_0763f7() {
+  float3 res =   dfdx(float3());
+}
+
+fragment void fragment_main() {
+  dpdx_0763f7();
+  return;
+}
+