[fa] add missing keys `generator.className.test` & `field_exists`

[datamweb]

Description Explain what you have changed, and why.

Checklist:

• [x] Securely signed commits
• [ ] Component(s) with PHPDoc blocks, only if necessary or adds value
• [ ] Unit testing, with >80% coverage
• [ ] User guide updated
• [x] Conforms to style guide