Move OpenGL extension query into renderer backend

src/renderer_gl/opengl_capabilities.cpp

@@ -344,6 +344,31 @@ pp::foundation::Result<OpenGlRuntimeInfo> query_opengl_runtime_info(
     });
 }
 
+pp::foundation::Result<std::vector<std::string>> query_opengl_extensions(
+    OpenGlExtensionQueryDispatch dispatch)
+{
+    if (dispatch.get_integer == nullptr || dispatch.get_string_indexed == nullptr) {
+        return pp::foundation::Result<std::vector<std::string>>::failure(
+            pp::foundation::Status::invalid_argument("OpenGL extension query callbacks must not be null"));
+    }
+
+    std::int32_t extension_count = 0;
+    dispatch.get_integer(extension_count_query(), &extension_count);
+    if (extension_count <= 0) {
+        return pp::foundation::Result<std::vector<std::string>>::success({});
+    }
+
+    std::vector<std::string> extensions;
+    extensions.reserve(static_cast<std::size_t>(extension_count));
+    for (std::int32_t index = 0; index < extension_count; ++index) {
+        const char* extension = dispatch.get_string_indexed(
+            extension_string_name(),
+            static_cast<std::uint32_t>(index));
+        extensions.emplace_back(extension != nullptr ? extension : "");
+    }
+    return pp::foundation::Result<std::vector<std::string>>::success(std::move(extensions));
+}
+
 OpenGlDefaultClear panopainter_default_clear() noexcept
 {
     return OpenGlDefaultClear {