FIO-9196: Fixed issue with getting default value instead of requested value in Day component

[roma-formio]

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-9196

Description

Issue: The DataTable is calling the method getValueAsString to get the string representation of a value from the submission. The getValueAsString method internally calls the getDate method, which uses the default value of the component if the value is empty. This results in the DataTable showing the default value instead of a blank.

Solution: Add a check to see if the value is not set. If the value is not set, return an empty string without calling the internal method getDate.

How has this PR been tested?

Unit tests and manually

Checklist:

• I have completed the above PR template
• 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