Allow passing user config to tests

[NathanFlurry]

Need to be able to pass a custom user config to a module's test. At the moment it pulls the config from the backend.yaml.

Maybe this should be configurable so you can pass an entire backend.yaml config so the tests can be ran in isolation without a full project. This may be slow since it has to prebuild & migrate required dependencies, though.

[linear]

OGBE-85 Allow passing user config to tests

Need to be able to pass a custom user config to a module's test. At the moment it pulls the config from the backend.yaml.

Maybe this should be configurable so you can pass an entire backend.yaml config so the tests can be ran in isolation without a full project. This may be slow since it has to prebuild & migrate required dependencies, though.