Allow Unique Optional fields

[David-Lor]

Is your feature request related to a problem? Please describe.

I have defined a field which is Unique but also Optional. When a row with this field unset already exists, inserting a second row with the same unset field results in the Unique validation failing.

Describe the solution you'd like

The Unique validation should not affect unset fields on Optional fields.

Describe alternatives you've considered

No response

Additional context