feat(gx): add incomplete 'CGxDeviceGLSDL' (#2)

* chore(build): add vendored SDL 3.0.0 library

* chore(build): add vendored glew-cmake-2.2.0 library

* feat(console): in the presence of -opengl launch flag, change GxApi to OpenGl

* feat(gx): add uncompleted CGxDeviceGLSDL targeting Windows and Linux

* chore(build): change SDL3 linkage from shared (bad) to to static (good)

vendor/sdl-3.0.0/cmake/test/sdltest.c

@@ -0,0 +1,9 @@
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_test.h>
+
+
+int main(int argc, char *argv[]) {
+    SDLTest_CommonState state;
+    SDLTest_CommonDefaultArgs(&state, argc, argv);
+    return 0;
+}