VSA - custom stage fields with validation errors don't have red borders

Summary

As a follow up to !123710 (comment 1434376119), when creating/editing value streams, custom stage fields with validation errors don't have red borders around them.

Steps to reproduce

1. Create/edit value stream
2. Add custom stage and don't enter name or select start/end events
3. Submit form

What is the current bug behavior?

Custom stage fields with validation errors don't have red borders around them.

What is the expected correct behavior?

Custom stage fields with validation errors should have red borders around them as per Pajamas guidelines.

Relevant logs and/or screenshots

Screen_Recording_2023-06-16_at_1.51.23_PM

Possible fixes

Fix logic in hasFieldErrors method. We may want to check if the same issue is occurring in default stage fields as well.