Beta fixes: Optional Properties handling

[Totto16]

Since the new Beta of ts-for-gir the approach to optional parameters has changed, now everywhere Partial<XY.ConstructorProps> is used, instead of declaring each property in the ConstructorProps property?: xy

This breaks many things, and they all have to be changed, this wasn't caught before, since apparently no-one (including me) used the 4.0.0-beta.2 types.

I'll try to find all places and then squash it into one commit.

Here's a fun screenshot, of using this types with the beta-2 packages:

[swsnr]

@Totto16 You need to resolve merge conflicts here 🙂

[Totto16]

Merging this, since nothing changed, other than the merge conflict resolution

[Totto16]

Note: I released this and the previous commits to npm as 46.0.0-4.0.0-beta.3 in the next tag on npm and as a prerelease here on github