boa: support esm

[rickyes]

fixes: #173

Support export default and named export import.

/cc @yorkie

[CLAassistant]

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[yorkie]

Suggested change

	import Boa from '../lib/index.js';
	import boa from '../';

[rickyes]

Doesn't seem to automatically look for package.json.

[yorkie]

Weird, we have defined the main as "lib/index.js" at https://github.com/alibaba/pipcook/blob/master/packages/boa/package.json#L5.

[yorkie]

Thank you @rickyes I have commented some, and unit test is also required :)

[Txiaozhe]

LGTM except lint nit:)

[rickyes]

Thank you @rickyes I have commented some, and unit test is also required :)

Of course, when the deconstruction import is supported, unit tests will be added together.

[rickyes]

The named export is already supported, please review. @yorkie @Txiaozhe

[yorkie]

I have some comments for your changes, and we also need more tests, which needs cover builtins, base package and numpy.

[rickyes]

I have some comments for your changes, and we also need more tests, which needs cover builtins, base package and numpy.

Okay, I'll supplement the base library test.

[rickyes]

I've made some changes, please review them.

[yorkie]

@rickyes May I ask you to revert the code coverage? It seems that LGTM except that :)

[yorkie]

internal/modules/run_main.js:54
    internalBinding('errors').triggerUncaughtException(
                              ^

TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension "" for /home/runner/.node-spawn-wrap-5008-e0ba0a808e26/node
    at Loader.defaultGetFormat [as _getFormat] (internal/modules/esm/get_format.js:65:15)
    at Loader.getFormat (internal/modules/esm/loader.js:113:42)
    at Loader.getModuleJob (internal/modules/esm/loader.js:244:31)
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
    at async Loader.import (internal/modules/esm/loader.js:178:17)
    at async internal/process/esm_loader.js:55:9 {
  code: 'ERR_UNKNOWN_FILE_EXTENSION'
}

It seems the above error occurred.

[yorkie]

LGTM