[js/web] allow bundler import condition for not bundling wasm

[fs-eire]

Description

This gives a way for webapp developers to customize the bundler behavior regarding whether to bundle the wasm.

To avoid treating ort-wasm-threaded-simd.jsep.mjs and ort-wasm-threaded-simd.jsep.wasm as dependencies during the process of bundler build, use import condition onnxruntime-web-use-extern-wasm.

For webpack:

module.exports = {
  //...
  resolve: {
    conditionNames: ['onnxruntime-web-use-extern-wasm', 'import', 'module'],
  },
};

For esbuild:

await esbuild.build({
  //...
  conditions: ['onnxruntime-web-use-extern-wasm', 'import', 'module'],
})

For rollup:

import { nodeResolve } from '@rollup/plugin-node-resolve';

export default {
  //...
  plugins: [nodeResolve({
    exportConditions: ['onnxruntime-web-use-extern-wasm', 'import', 'module', 'development|production']
  })]
};

Motivation and Context

• [Web] No way to prevent the default wasm from being bundled #24009

[fs-eire]

Unfortunately, I didn't figure out a solution that allows bundler to achieve this without needing to modify any user code (bundler config).