[js/web] allow bundler import condition for not bundling wasm (#24014)

### Description
<!-- Describe your changes. -->

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
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->

- #24009

Author: fs-eire

js/web/package.json

@@ -72,23 +72,35 @@
         "import": "./dist/ort.node.min.mjs",
         "require": "./dist/ort.node.min.js"
       },
-      "import": "./dist/ort.bundle.min.mjs",
+      "import": {
+        "onnxruntime-web-use-extern-wasm": "./dist/ort.min.mjs",
+        "default": "./dist/ort.bundle.min.mjs"
+      },
       "require": "./dist/ort.min.js"
     },
     "./all": {
-      "import": "./dist/ort.all.bundle.min.mjs",
+      "import": {
+        "onnxruntime-web-use-extern-wasm": "./dist/ort.all.min.mjs",
+        "default": "./dist/ort.all.bundle.min.mjs"
+      },
       "require": "./dist/ort.all.min.js"
     },
     "./wasm": {
-      "import": "./dist/ort.wasm.bundle.min.mjs",
+      "import": {
+        "onnxruntime-web-use-extern-wasm": "./dist/ort.wasm.min.mjs",
+        "default": "./dist/ort.wasm.bundle.min.mjs"
+      },
       "require": "./dist/ort.wasm.min.js"
     },
     "./webgl": {
       "import": "./dist/ort.webgl.min.mjs",
       "require": "./dist/ort.webgl.min.js"
     },
     "./webgpu": {
-      "import": "./dist/ort.webgpu.bundle.min.mjs",
+      "import": {
+        "onnxruntime-web-use-extern-wasm": "./dist/ort.webgpu.min.mjs",
+        "default": "./dist/ort.webgpu.bundle.min.mjs"
+      },
       "require": "./dist/ort.webgpu.min.js"
     }
   },