Added various features to Openkh.Tools.LayoutEditor.

[Kite2810]

Adds:

• Add/Remove Layout Index Button
• Add/Remove Sequence Property Button
• Add/Remove Animation Group Button
• Add "Import IMGD Texture Button (need to convert a png to imd, with the Openkh Image Viewer Tool)
• Add "Remove Last Texture" Button (can't remove indexes, if less than 2)
• Save Shortcut, bypassing ImGui's modal blocking. (no need to close the Child Window anymore)

Made the Child Window Scrollbar Bigger.

Fixed the "Remove Sprite Group" Button to account for Animation Groups

Summary by CodeRabbit

Release Notes

• New Features

  • Added texture import and management capabilities in the layout editor.
  • Added ability to create and remove sequence groups.
  • Added animation group management with add/remove controls.
  • Improved right panel with scrollable content for better navigation.

• Bug Fixes

  • Improved keyboard support to detect both left and right Ctrl keys.
  • Fixed animation references to properly update when removing sprite groups.

• Improvements

  • Enhanced layout spacing and panel sizing for better usability.

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