FIO-8556: Test coverage metrics

[mikekotikov]

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-8556

Description

What changed?

Added tests coverage with nyc library

Dependencies

None

How has this PR been tested?

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

[johnformio]

@mikekotikov the build failed. Your coverage thresholds are too high. You will need to set these after you run coverage the first time to know what the initial settings should be.

ERROR: Coverage for lines (15.86%) does not meet global threshold (80%)
ERROR: Coverage for functions (15.33%) does not meet global threshold (79%)
ERROR: Coverage for branches (19.05%) does not meet global threshold (63%)
ERROR: Coverage for statements (15.81%) does not meet global threshold (81%)