[Feat|Fix|Improvement] (All): Continue building the basic structure.

Feat: implement MG_Impl/Buffer
Feat: implement MG_State/ErrorState and integrate it into MG_State/GLContext
Feat: add buffer deletion management
Feat: introduce `INSERTION_POINT` (https://github.com/MobileGL-Dev/MobileGLCodeManager)
Feat: add tests about MG_Impl/Buffer and buffer deletion feature
Feat: add several converters
Fix: fix some compiling errors
Fix: fix some incorrect behaviors in MG_State/Buffer
Improvement: remove some current statements at the beginning of the source file, which will be added uniformly soon
Improvement: optimize some naming

MobileGL/MG_Util/Debug/Log.cpp

@@ -7,15 +7,15 @@ namespace MobileGL {
 
         constexpr char* GetOSName() {
 #if defined(_WIN32)
-            return "Windows";
+            return (char*)"Windows";
 #elif defined(__ANDROID__)
-            return "Android";
+            return (char*)"Android";
 #elif defined(__APPLE__)
-            return "macOS";
+            return (char*)"macOS";
 #elif defined(__linux__)
-            return "Linux";
+            return (char*)"Linux";
 #else
-            return "UnknownOS";
+            return (char*)"UnknownOS";
 #endif
         }