Option to disable adding `.strict()` to schemas.

[bostjanpisler]

Is your feature request related to a problem? Please describe. I would like to extend the created schemas with .merge and .omit which is not possible for schemas with .strict()

Describe the solution you'd like Allow adding optional disableAddingStrict = true to generator Client to disable .strict() on all schemas.

[dshunfen]

This would be very useful. There are often hidden-to-enduser fields that I would like to omit, and sometimes modifications to existing fields (nully, etc.) that would come in handy.

[ekuzu]

Hey @chrishoermann, What do you think about adding this optional? That would be really helpful to customize schemas.