onnxruntime

ORT Web build script (#12643)

**Description**:
Adding a few scripts to enable user to build ORT Web in a simpler way.

**Instructions**:
Under ROOT\js folder you will have 2 scripts - 
1. "Build_web.bat" - for Windows users
1. "Build_web.sh" - for Linux users

Default build configuration is "Release" to change the build configuration just add to the script call the flag "--config <Desired configuration>". As example:
```
build_web.bat --config Debug
```

Co-authored-by: shalvamist <shalva.mist@microsoft.com>