Add examples to SDL.sln

[Susko3]

Description

Each C example from the examples/ directory is added as a Visual C++ project to SDL.sln, making it easy to test and see the examples on Windows. The projects include the .c file and README.txt. To avoid code duplication in .vcxproj files, common code is moved to Directory.Build.props.

The project files can be automatically generated with the provided generate.py python file, but they still need to be manually added to the appropriate place in the VS solution (using Add existing project).

The initial project files were made with JetBrains Rider and not Visual Studio, but they do work in VS. There might be slight differences if you compare with the test projects.

Existing Issue(s)

• Resolves [Feature request] Add examples to SDL.sln (visual studio solutions) #11207

[slouken]

This seems reasonable to me, @icculus?

[madebr]

I'm curious whether the examples rebuild when switching between Configuration (Release|Debug)and Platform (Win32|x64).

[Susko3]

It does rebuild, both the example and the main SDL project.

For some reason, the examples don't work when I build Win32. Runtime error about SDL3.dll missing. The tests work fine /shrug.

[madebr]

This looks fine to me as a first version.

Directory.Build.props is a user-defined file that provides customizations to projects under a directory

Our vcxproj projects contain a lot of repeated code. Perhaps we should add all common code in a shared .props.
I did such a thing in #7257 (for the wrong reason).
The only thing we lose with such change is easy modification of target options in the Visual Studio IDE.

[icculus]

I'm not against this, but we're absolutely going to forget to add new programs over time.