Contributed by a Nheko user starting with S.

See also:
https://daniel.haxx.se/blog/2023/01/08/copyright-without-years/
https://hynek.me/til/copyright-years/

This should reduce payload size a lot

According to LorenDB's First Law of Software Development, once a developer has committed or merged a new feature, he will find at least one problem with the implementation.

I realized that I was constructing the room info items with some parameters out of order, which required a rather urgent fix. Furthermore, I fixed the image decoding algorithms in the QDBusArgument operator. Finally, I switched the API version parameter back to QString, since passing it as a QVersionNumber would create a problem for non-Qt API users.

On the general improvements side of things, I added some handy wrappers for D-Bus calls so that other devs that copy the NhekoDBusApi files to use for their own applications won't have to go to the effort of making the D-Bus calls themselves.

This adds functionality for viewing joined rooms and activating rooms.