[OpenVINO-EP] Optimize MCR Docker image size (#3732)
* updated dockerfile.openvino
* Group all RUN commands and add a 'cd WORKDIR' betwen each
* Update doc with installer and build info
Highlight usage of Online installer package.
Specify --rm option during docker build to avoid caching layer.
Co-authored-by: avidiyal <akhila.vidiyala@intel.com>
