chore: update GIMP keyboard shortcuts configuration

[gabrielalmir]

Update various keyboard shortcuts in GIMP configuration file to improve usability and avoid conflicts, based on issue #141

[Copilot]

Pull Request Overview

This PR updates GIMP keyboard shortcuts configuration to improve usability and resolve potential conflicts. The changes reassign shortcuts for common operations like fill commands, export, image duplication, and layer merging to more intuitive or accessible key combinations.

• Modified fill foreground/background shortcuts to use BackSpace-based combinations
• Updated file export shortcut to a more complex multi-key combination
• Assigned new shortcuts for image duplication and layer merging operations

[Copilot]

[nitpick] The keyboard shortcut 'w' requires four simultaneous key presses, which may be difficult for users to execute reliably. Consider using a simpler two or three-key combination for this frequently used export function.

Suggested change

	(action "file-export" "<Primary><Shift><Alt>w")
	(action "file-export" "<Primary><Shift>e")

[gabrielalmir]

Still, the goal is for it to be as close to Photoshop as possible, specially for the must common keyboard shortcuts.

[gabrielalmir]

The changes include modifying existing shortcuts for actions like filling with foreground/background colors, exporting files, duplicating images, and merging layers.

Updated keyboard shortcuts:

• Foreground/Background Fill:

  • Changed the shortcut for filling with the foreground color from <Primary>comma to <Primary>BackSpace.
  • Changed the shortcut for filling with the background color from <Primary>period to <Alt>BackSpace.

• File Export:

  • Updated the export shortcut from <Primary>e to <Primary><Shift><Alt>w.

• Image Operations:

  • Added a new shortcut <Primary>j for duplicating an image.
  • Changed the shortcut for merging layers from <Primary>m to <Primary>e.