FIO-9678: fixed an issue where number value is not displayed is submission grid

[TanyaGashtold]

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-9678

Description

What changed?

Before, toString method returned undefined for number type. This PR fixes it.

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