Default all users R Studio config to tick every 'R Diagnostics' box

[paulsharpeY]

To teach users how to debug their code, we should enable all R Diagnostics (Options > Code > Diagnostics). This is a sensible default for new users, which they can override later.

In R Studio 1.3+ global config can be set in /etc/rstudio/rstudio-prefs.json.

Requires a test of whether the global config works for existing users who may already have their own rstudio-prefs.json.

[paulsharpeY]

Here's a link to the code diagnostics docs which are otherwise hard to find.

[paulsharpeY]

Admin docs for global settings.