Support loading invalid configurations in the plugin test framework

[dlvenable]

Is your feature request related to a problem? Please describe.

I want to have a simple way to load invalid configurations and verify that the plugin fails to load within the plugin test framework.

Describe the solution you'd like

I'm investigating two approaches:

1. Define specific invalid configurations and make sure they are invalid.
2. Define a valid configuration and then a collection of mutations to perform on it.

Either approach could be generated as dynamic tests automatically.

Additional context

This will build on #5917 and the work submitted in #6138.