Paintroid-802: Add clear button to clipboard tool

[jShubh-AD]

This PR adds a Clear Clipboard action to the Clipboard tool options.
Users can now clear copied clipboard content directly from the toolbar.
The update also improves the clipboard UI by adding labeled action chips with horizontal scrolling for better usability.

New Features and Enhancements

• Added Clear Clipboard action chip to the Clipboard tool options UI.
• Allows users to clear copied clipboard content directly from the actions.
• Added Text name in the chip and horizontal scroll for better UX .
• Jira Ticket: PAINTROID-802

Refactor and Bug Fixes

• chipIcon now supports Widget type instead of Icon in CustomActionChip.
• onPressed is now nullable to support disable states.

Tests

• Refactor: widget test for clipboard_tool_test now finds CustomActionChip with text (e.g. 'Copy', 'Paste').
• Added: integration tests for clipboard_tool_test.

Demo

• Current behavior

• paitroid_current_behavior.mp4

• Expected behavior

• paitroid_expected_behavior.mp4

Checklist

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