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)
• [x] My changes generate no new warnings
• [x] My changes include tests that prove my fix is effective (or that my feature works as intended)
• [x] New and existing unit/integration tests pass locally with my changes
• [x] Any dependent changes have corresponding PRs that are listed above

[mikekotikov]

Closing, since another PR is made to fix this