use WebGPU EP instead of JSEP in WebAssembly (#24856)
### Description
This PR allows to use WebGPU EP in `onnxruntime-web` NPM package.
### Migration Plan
Currently, there are 2 different EPs implemented the WebGPU backend of
onnxruntime-web. They are JSEP and WebGPU EP. The migration plan is to
replace the JSEP with WebGPU EP and eventually remove the JSEP. The plan
contains the following stages:
- STAGE 1: enable WebGPU EP on onnxruntime-web in local build. (Done)
- **STAGE 2: enable WebGPU EP on onnxruntime-web in the public package.
(This PR)**
- STAGE 3: remove JSEP from onnxruntime-web.
### Package consumption changes
- Default import (`import 'onnxruntime-web'`) and CPU only import
(`import 'onnxruntime-web/wasm'`) keeps their previous behaviors.
- WebGPU import (`import 'onnxruntime-web/webgpu'`) will now use WebGPU
EP instead of JSEP. Previously it was the same as default import.
- WebGPU import will use a different suffix for the .mjs and .wasm name
(which was `.jsep`):
- ort-wasm-simd-threaded<b>.asyncify</b>.mjs
- ort-wasm-simd-threaded<b>.asyncify</b>.wasm
- The suffix `.asyncify` is used as `.jspi` is planned for future. They
are 2 different ways of emscripten's async implementation (sync C++
function calls async JS function)
