improve the mapping that determines which datalab issue types to run based on which args the user provided

[jwmueller]

we want this mapping to be more forwards compatible, such that it's easier to add new issue types.
We keep forgetting to update the current mapping each time we add new issue types.

Instead perhaps we could use a try/except framework that simply suppresses errors where the issue manager was attempted to run with missing key arguments that it required. I'm not sure the best approach here, but something that we don't need to update with every single new issue type would be ideal.