[Fix] (MG_Util, MG_State): reject reserved GLSL identifiers glslang accepts

glslang parses "packed" and "row_major" as plain identifiers outside a
layout(...) list and accepts the reserved image*Shadow names outright.
A comment/preprocessor-aware pre-scan in the compile path now fails such
shaders with a proper info log, while layout(packed)/layout(row_major)
qualifier lists stay legal (uniform_block family still passes).
KHR-GL31/32/33.CommonBugs.CommonBug_ReservedNames now pass.

MobileGL/MG_State/GLState/ProgramState/ShaderObject.cpp

@@ -169,6 +169,15 @@ namespace MobileGL::MG_State::GLState {
             }
         }
 
+        const std::optional<String> reservedError =
+            MG_Util::ShaderTranspiler::FindReservedIdentifierViolation(compileSource);
+        if (reservedError) {
+            m_compileStatus = false;
+            m_shader.reset();
+            m_infoLog = *reservedError;
+            return;
+        }
+
         // Compile for OpenGL here, so that we can do validation and link
         // like a real OpenGL driver at linking stage
         // Will compile for other backends later.