Think about adding add `Base.disableWhen`

[MangelMaxime]

Signature would be

let disableWhen
        (condition: 'Values -> bool)
        (form: Form<'Values, 'A, 'Attributes>)
        : Form<'Values, 'A, 'Attributes>
        =
        Base.disableWhen condition form

I am unsure if we should add this helpers or if this would lead to bad practice in the library code.