The patch file used by the .devcontainer is needed only by  the build-install-ngx-voms.sh script. This script could use the patch file in the project home dir instead of the copy in the container.

Add an echo in the container specifing that the patch file must exists in the directory where the user runs the script.

Add  a check in the script: if the patch file isn't found, the script adivses the user and exits with an error.

The yum install commands were copy-&-paste from the 3  original images.
Now all the repo are installed first; then, they are followed by all the other packages merged together in a single yum install command.

To create the image defined in this dockerfile, we've merged three differend images:
 * storm2/build/base
 * storm2/build/ngx-voms-build [issue-17]
 * storm2/ngx_http_voms_module/.devcontainer
Each image has this own 'yum install' command with the packages needed for that layer.

With this commit, all the packages are installed in a single layer to reduce the image dimension.
All the 'yum install' commands are grouped in the setup.sh script.

* To reduce the image dimension, two RUN commands are merged in one single layer.
* All packages are installed with a single command.
* remove cern and garr mirrors
* the clean commands are the last instructions in the layer
* sudo is installed only in the dockerfile

To create the vscode user, the provide_user.sh script is used. With this script the comand line appearance is improved with colors and branch informations

The script can be used both for the devcontainer and for the continuous
integration.