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/main_lib.c

@@ -0,0 +1,34 @@
+#include <SDL3/SDL.h>
+#define SDL_MAIN_HANDLED /* don't drag in header-only SDL_main implementation */
+#include <SDL3/SDL_main.h>
+
+#include EXPORT_HEADER
+
+#ifdef _WIN32
+#include <windows.h>
+BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved) {
+    return TRUE;
+}
+#endif
+
+int MYLIBRARY_EXPORT mylibrary_init(void);
+void MYLIBRARY_EXPORT mylibrary_quit(void);
+int MYLIBRARY_EXPORT mylibrary_work(void);
+
+int mylibrary_init(void) {
+    SDL_SetMainReady();
+    if (SDL_Init(0) < 0) {
+        SDL_Log("Could not initialize SDL: %s\n", SDL_GetError());
+        return 1;
+    }
+    return 0;
+}
+
+void mylibrary_quit(void) {
+    SDL_Quit();
+}
+
+int mylibrary_work(void) {
+    SDL_Delay(100);
+    return 0;
+}