[dev-5] fix: FluentDatePicker date validation not updated by calendar selection

[NathanWilliamsCloca]

🐛 Bug Report

The FluentDatePicker date format validation does not update after selecting a date from the calendar.

💻 Repro or Code Sample

1. Navigate to the form example page on the demo site: https://fluentui-blazor-v5.azurewebsites.net/Forms
2. Enter something that is not a date into the date input and trigger validation.

3. Select a date from the calendar and trigger validation again. The error will remain even though the date is now in a valid format.

🌍 Your Environment

OS & Device: Windows 11 on PC
Browser: Google Chrome
.NET version 10
Fluent UI Blazor library Version 5.0.0-rc.5-26219.1