feat: Display detailed error message when loading of project fails (#1135)

In order to do this I add to make some other additions :
- Add a warning popup (TODO, maybe add some icons to differentiate
error/warning popups in a future PR ?)
- create showError() and showWarning() functions, as helpers to show a
message both to the logs and as a popup

plugins/builtin/include/content/helpers/notification.hpp

@@ -0,0 +1,10 @@
+#pragma once
+
+#include <content/popups/popup_notification.hpp>
+
+namespace hex::plugin::builtin {
+
+    void showError(const std::string& message);
+
+    void showWarning(const std::string& message);
+}

plugins/builtin/include/content/popups/popup_notification.hpp

@@ -1,6 +1,9 @@
+#pragma once
+
 #include <hex/ui/popup.hpp>
 
 #include <hex/api/localization.hpp>
+#include <hex/api/imhex_api.hpp>
 
 #include <functional>
 #include <string>
@@ -53,6 +56,14 @@ namespace hex::plugin::builtin {
         }) { }
     };
 
+    class PopupWarning : public impl::PopupNotification<PopupWarning> {
+    public:
+        explicit PopupWarning(std::string message)
+        : PopupNotification("hex.builtin.common.warning", std::move(message), [this]() {
+            Popup::close();
+        }) { }
+    };
+
     class PopupError : public impl::PopupNotification<PopupError> {
     public:
         explicit PopupError(std::string message)