Add WebNN-native binding for Node.js to expose WebNN JavaScript API

[fujunwei]

webnn-polyfill has 600 test cases to test APIs, ops and models. To avoid porting of these tests to C++, it would be useful to run these JS tests with node.js. The WebNN-native binding is to bind WebNN-native C++ API with addon.

This PR depends on #10.

[BruceDai]

Thanks much @fujunwei!

Current webnn-polyfill@5c5e9f6 has 615 test cases (614 passing / 1 pending by WebNN Polyfill API):

• API tests total: 84, passing 84
• Ops tests total: 266, passing 266
• Models tests total: 15, passing 14, 1 pending
• CTS tests total: 250, passing 250

Following node/README.md, I verified this PR:

1. built webnn-native by DML backend, when executing npm test command to run all tests of webnn-polyfill,
   got 386 passing / 1 pending / 228 failing
2. built webnn-native by OpenVINO backend, when executing npm test command to run all tests of webnn-polyfill,
   got 385 passing / 1 pending / 229 failing

Let's look at pass status of running Ops tests and Model tests:

Backend	Ops tests (npm run test-ops)	Model tests (npm run test-models)
DML	128 passing 138* failing	14 passing 1pending
OpenVINO	126 passing 140* failing	14 passing 1 pending

Above '14 passing 1 pending' of running Model tests are same as test result by WebNN polyfill API.
And 138 failing ops tests by DML backend and 140 failing ops tests by OpenVINO backend are most with unimplemented op features likes conv2d support transpose option, and those unimplemented ops (div/exp/gru/instance_norm/max/min/pad/pow/reduce/resample/sigmoid/slice/split/squeeze/sub/tanh/transpose) by WebNN native.

WebNN polyfill Supported ops	WebNN native Supported status
add	YES
batch_norm	YES
clamp	YES
concat	YES
conv2d	YES
div	NO
exp	NO
gemm	YES
gru	NO
instance_norm	NO
leaky_relu	YES
matmul	YES
max	NO
min	NO
mul	YES
pad	NO
pool2d	YES
pow	NO
reduce	NO
relu	YES
resample	NO
reshape	YES
sigmoid	NO
slice	NO
softmax	YES
split	NO
squeeze	NO
sub	NO
tanh	NO
transpose	NO

Test logs:

1. test_log_by_webnn_nodejs_binding_with_dml.txt
2. test_log_by_webnn_nodejs_binding_with_openvino.txt

[huningxin]

Great work, thanks @fujunwei . I left some comments, please take a look.

[fujunwei]

@huningxin Done, thanks.

[huningxin]

Thanks for updating the PR. It looks good to me.

[huningxin]

Based on the feedback from WebML WG Teleconference – 24 June 2021, both the webnn-polyfill tests and webnn-native implementation on native ML APIs are useful to inform the spec development. This PR specifically enables running the webnn-polyfill tests on native ML API implementation. With that, I am going to merge this PR and unlock the development of other features, like new API change and ops.

Thanks much @fujunwei and @BruceDai !