Extract canvas stroke commit and brush preset services

src/legacy_brush_preset_services.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include "node_panel_brush.h"
+
+#include <string>
+
+namespace pp::panopainter {
+
+class LegacyBrushPresetServices final {
+public:
+    explicit LegacyBrushPresetServices(NodePanelBrushPreset& owner) noexcept;
+
+    bool save();
+    bool restore();
+    bool export_ppbr(const std::string& path, const NodePanelBrushPreset::PPBRInfo& info);
+    bool import_ppbr(const std::string& path);
+    bool import_abr(const std::string& path);
+    bool import_brush(const std::string& path);
+    void clear_brushes();
+
+private:
+    NodePanelBrushPreset& owner_;
+};
+
+} // namespace pp::panopainter