Feature request: `tsify(required)`

[FredrikNoren]

I quite often find myself in a spot where I want serde(default) so that old values can be de-serialized, but I don't want the typescript type of be optional. It would be amazing if there was a tsify(required) so that I could do this:

#[tsify(required)]
#[serde(default)]
pub field: String;

which would produce the type:

{
   field: string
}

Or even better, I think I would prefer if #[serde(default)] wouldn't make the field optional in the first place.