FIO-8389: Fix EditGrid with Empty/Is Not Empty conditional logic in there

[mikekotikov]

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-8389

Description

What changed?

Previously, formio.js would fail to call 'isEmpty' method if it doesn't exist. This PR adds a check to make sure it exists, before calling.

Dependencies

@formio/core:98

How has this PR been tested?

I added automated tests to cover conditionals cases in Edit Grid with Text field and Checkbox components, corresponding to the scenario where this bug was uncovered.

Checklist:

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• My changes generate no new warnings
• My changes include tests that prove my fix is effective (or that my feature works as intended)
• New and existing unit/integration tests pass locally with my changes
• Any dependent changes have corresponding PRs that are listed above

[brendanbond]

Can we discuss this? This issue was also reported by an additional customer, but it seems to me this doesn't solve the root cause of the problem (because it is unsolvable? how does the conditional logic know which row is empty?).

[mikekotikov]

Closing, since another PR is made to fix this