What problem does this address?

Currently our tests don't have robust support for testing fields when they're nested within a repeater or flexible content layout.

This makes it difficult to ensure we don't cause regressions, etc.

What is your proposed solution?

We should create some abstract tests to test fields as sub-fields of Flex Layouts / Repeaters, and implement them in all the field type test suites.

What alternatives have you considered?

Leaving these cases untested 😱

Additional Context

There's similar abstract tests for clone and block fields that we should be able to follow patterns for to implement these tests in a re-usable pattern