Do not enable hot-relaod when studio package not installed

Register a nuxeo instance, start it, click on hotrelaod from the BDE. It will try to hot reload the package even if it has never been installed before. This causes some situations where it doesn't want to hot reload the packages because some dependencies were not installed initially.

Expected behaviour:
If studio project hasn't been installed in command line before, Disble hot reload button with a message / warning that says studio package should be installed with mp-install package name (display the command to use for the installation).