refactor: image tool class added

[Onetchou]

• image related functions have been moved from mainwindow.cpp to an ImageTool class in image_tool.cpp
• image related source files have been moved into an image subdirectory

[what-the-diff[bot]]

PR Summary :tada:

Wow! That was quite a refactor. Let's take a look at how your hard work has transformed and streamlined our codebase. :muscle:

• Streamlined Handling of Image Functions 🖼️

  In src/app/seamly2d/mainwindow.cpp, many image-related functions were removed (such as handleImportImage, addImage, handleDeleteImage, and others). Then handleImportImage was renamed to handleImageTool to clarify its purpose.

• Renewed Organization of Functions 🗂️

  Order of some functions, such as ClosedInsertNodesDialog and setStatusMessage, was markedly rearranged to improve code readability and maintainability.

• Introduction of New Class - ImageTool 🆕

  A fresh new class ImageTool was sprung into src/libs/tools/images/image_tool.cpp. This class introduces some cool new functions like addImage, handleDeleteImage, and more. These changes make our codebase more modular and easier to understand!

• Trimming Down MainWindow 🦾

  The previously heavy-lifting MainWindow, is now much leaner, thanks to the removal of several functions and variables associated with image manipulation. They've found a more fitting home in the ImageTool class.

• Exciting File Relocation Activities 🚚

  Last but not least, multiple files (image_dialog.h, image_item.h, image_dialog.cpp, image_item.cpp, image_tool.cpp, image_dialog.ui) have been relocated to align with our new structure under src/libs/tools/images/.

• Updated Build Instructions 🛠️

  Don't worry about struggling to keep up! We've taken care to update the HEADERS and SOURCES variables in tools.pri to match the new locations of these files.

All these changes are setting us up for further growth 🌱 and will make our journey ahead smoother! Great job, and keep those fantastic contributions coming! 🚀 This PR certainly brought our code to a better place. Let's keep this momentum going, developers! 💜 🎉

[Onetchou]

Fixes #1103