fix: robust OpenGL probing, simplify naming, and add debug support

- extract JSON block from noisy subprocess output to handle log noise
- use 'offscreen' platform and disable ASAN leaks for probe subprocess
- rename BackendType::GLES to BackendType::ES and "GLES" to "ES" across UI and logs
- add support for detecting and reporting OpenGL Debug Context availability
- enable DebugContext in QSurfaceFormat if supported by hardware
- remove "core" suffix from OpenGL version strings
- fix 64-bit precision and Windows variable declaration warnings
- simplify Windows GPU enablement declarations to a single line each

Author: nschimme

src/opengl/OpenGLProber.cpp

@@ -23,14 +23,9 @@
 #ifdef WIN32
 #include <windows.h>
 
-extern "C" {
 // Prefer discrete nVidia and AMD GPUs by default on Windows
-__declspec(dllexport) extern DWORD NvOptimusEnablement;
-__declspec(dllexport) extern int AmdPowerXpressRequestHighPerformance;
-
-__declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
-__declspec(dllexport) int AmdPowerXpressRequestHighPerformance = 1;
-}
+extern "C" __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
+extern "C" __declspec(dllexport) int AmdPowerXpressRequestHighPerformance = 1;
 #endif
 
 namespace {

tests/testopengl.cpp

@@ -24,7 +24,7 @@ private slots:
         QCOMPARE(OpenGLConfig::getGLVersionString(), std::string("GL4.5"));
     }
 
-    void testParseSurveyResult_GLES()
+    void testParseSurveyResult_ES()
     {
         OpenGLProber prober;
         QByteArray json = R"({"backend": "ES", "major": 3, "minor": 1, "debug": false})";