Add skipPermissionCheck field to context and repsect it in to validateDocument and validat…

[doronrk]

…eModifer

This behavior defaults to false.

[SachaG]

Should this be on the context though? That feels weird since the context is not specific to a mutation or a permission check. I'd probably pass a fourth options argument and put the property on that instead, and then base that on an argument of the mutator function (maybe have validateData and validatePermissions while keeping the current validate for backwards compatibility, which would do both?)