iologik tests: abstract the DI tests to avoid repetition of code

## Where?
IOC test framework, there is almost identical code for the 1210 and 1242 for testing the DI aspects which should be refactored into the shared code options for the iologik 1200 series

## How?
Not enough time to refactor this before needing to proceed to review in order to keep up with a build schedule

## Reproducible?
N/A

## Acceptance criteria
- [ ] The moxa 12xx base tests includes the DI tests
- [ ] The tests for the 1210 and the 1242 both reference the DI tests in the base code
- [ ] All the moxa iologik tests still pass

## How to Test
_verbose instructions for reviewer to test changes
(**Add before making a PR**)_