feat(callbacks): add onLayerInteractionEnd

[saif-ellafi]

PR Checklist (Required)

Please ensure your PR meets the following requirements:

• The commit message follows our guidelines: https://github.com/hm21/pro_image_editor/blob/stable/CONTRIBUTING.md#style-guides
• I have run dart format . in the terminal and committed any changes.
• I have run dart analyze . in the terminal and addressed any issues.
• I have run flutter test in the terminal and addressed any issues.
• I have pulled from the stable branch before committing.
• I have updated the CHANGELOG.md file with my changes (For the version, you can use X.X.X, I will later bump it after it's merged).
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PR Type

Please indicate the types of changes this PR introduces by checking the relevant boxes:

• Bugfix
• Feature
• Performance
• Refactor (no functional or API changes)
• Code style updates (e.g., formatting, local variables)
• Documentation updates
• CI-related changes
• Other... Please describe:

Current Behavior

It is not possible to trigger events once the interaction with a layer finishes.

Issue Number: N/A

New Behavior

This PR adds an onLayerInteractionEnd callback to allow taking action after the "release" of a layer in the editor.

Breaking Changes?

Does this PR introduce a breaking change?

• Yes
• No

Additional Information