consolidate all error/warnings the same Error type

[dagda1]

I was about to look at #605 but I think a good first step would be if all error messages or warnings that are persistable had the same structure.

We could use the ErrorDetails type in @bigtest/suite and add a severity field to distinguish whether it is a warning or error.

This mainly affects the bundler and any generic error handling that would need abstracted or updated to deal with rollup's sometimes odd error objects.