OC-27873 Do not show eConsent items in Form Designer if the parent form is in an invalid event

[umangzala-oc]

https://jira.openclinica.com/browse/OC-27873

• The eConsent Signature item type in Form Designer was previously visible in any event context where the study's eConsent module was ACTIVE or PENDING. This ticket adds a second gate: the form must also be opened from a Non-Repeating Visit event.
• Signature item is hidden for Repeating Visit events and all Common events, and visible only for Non-Repeating Visit events (or Library editing where no event context exists).