Boutiques disabled input issue in before_form and after_form

[natacha-beck]

In ensemblex for now each input is set to optionnal. It allow a user to launch a task without any input files.

The issue is the following if they are setup to optional false the before_form and after_form are too strict.

before_form will not allow the user to go to the form for example if a user select only one wordir it will raise an error.

In after_form only inactive input are ignored not disabled one.

[natacha-beck]

@prioux Thanks for the comment I look at it, but I still have to do some more verification. Will let you know when it seems ok on my side.