Add disableClear property to hide clear button in igc-combo component

[Copilot]

• Explore repository structure and locate igcCombo component
• Understand how boolean properties are implemented in combo.ts
• Review renderClearIcon method and how it's currently used
• Add new disableClear property to combo component
• Update renderClearIcon to respect the new property
• Add tests for the new property
• Update Storybook argTypes for the new property
• Run type checking (passed)
• Run linting (passed)
• Run security checks (CodeQL - 0 alerts)
• Verify implementation follows existing patterns
• Optimize condition check order for performance

Summary

Added a new disableClear boolean property to the igc-combo component that hides the clear button (X icon) when set to true.

Changes:

1. combo.ts: Added disableClear property with @property decorator, attribute name disable-clear, default value false
2. combo.ts: Updated renderClearIcon() to hide button when this.disableClear || this._selection.isEmpty (optimized check order)
3. combo.spec.ts: Added 2 unit tests to verify the property works correctly
4. combo.stories.ts: Added property to Storybook argTypes for documentation

Usage:

<igc-combo disable-clear></igc-combo>

or

combo.disableClear = true;

The implementation is minimal, follows existing patterns, and maintains backward compatibility (default is false). The condition check order has been optimized to check disableClear first for better performance.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Provide an option for igcCombo to disallow clearing the value (i.e. remove the X button)</issue_title>
<issue_description>Estimated Delivery Sprint - Sprint X

• Research
• Specification
• Component and tests implementation
• API Documentation
• Design implementation
  </issue_description>

<agent_instructions>The igxCombo needs a new option, which hides the clear value button when set.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

Fixes #1516

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[kdinev]

@copilot Do the disableClear check first, because if the property is set to true, then the logic doesn't need to get to an isEmpty check ever. It would be slightly more performant.

[Copilot]

Updated the condition order to check disableClear first for better performance: ?hidden=${this.disableClear || this._selection.isEmpty} (commit: b4b73b5)