Diagnostics errors due to modules not setup yet

Running diagnostics before module setup, causes some errors:

1. Before Tor is installed, running all diagnostics results in a FileNotFoundError for /var/lib/tor/state.
2. After Tor is installed, running all diagnostics shows a number of failures for other modules where the required packages are not installed yet.

I think we can skip diagnostics for modules that have not been setup, and show "skipped" as the result.