Build and Release Qt5 NuGet packages to version 5.15

[ghost]

See Title, in process

[buddhi1980]

Great! This upgrade is really needed, because It hart to keep compatibility of the code for wide range of Qt versions. Thanks a lot!

[ghost]

This requires update of Visual Studio Solution to 2022.

[buddhi1980]

Does Appveyor support VS 2022?

[ghost]

I hope so, we can cross that bridge when required. Right now, I cannot get the binary to link. In essence, each and every NuGet for the windows build requires recompilation with the same compiler version. My plan is to add all the NuGet build scripts into the contrib folder foreach dependency.

[buddhi1980]

I like the idea to add NuGet build scripts to the contrib folder. Will be easier in the future to update all needed binaries.