FIO-8597: fixed an issue with an empty array value for a number component with multiple values enabled

[KatrinKhilko]

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-8597

Description

Added condition to skip validation if value submitted for a number component with multiple values enabled is [].

Dependencies

n/a

How has this PR been tested?

Added test.

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