Introduce project_id in addition to experiment_id

[bpkroth]

Experiment's can often be related (e.g., by only changing a handful of tunable parameters).

In that case, we may wish to reuse some of the resources used for a group of experiments inside an RG (e.g., the VNet).

To do this, we could

• [ ] add a $project_id as another built-in variable (like experiment_id and trial_id) that can be used for templating out other variables inside configs.
• [ ] we should document all of these built in variables that can be used inside configs

[bpkroth]

Or maybe resourceGroup is good enough for that?