feat(components): [ColorPicker] add slot custom trigger

[lequangdongg]

Please make sure these boxes are checked before submitting your PR, thank you!

• Make sure you follow contributing guide English | (中文 | Español | Français).
• Make sure you are merging your commits to dev branch.
• Add some descriptions and refer to relative issues for your PR.

Description

• With color picker, i i want a custom default trigger with any element

🤖 Generated by Copilot at fbd6d5c

This pull request enhances the color-picker component by adding a trigger slot and removing unused icons. The trigger slot lets users customize the color-picker trigger element in color-picker.vue.

Related Issue

Fixes #___.

Explanation of Changes

🤖 Generated by Copilot at fbd6d5c

• Add a trigger slot to the color-picker component to allow customizing the trigger element (link)
• Remove unused imports of ArrowDown and Close icons from the @element-plus/icons-vue package (link)

[pull-request-triage]

👋 @lequangdongg, thank you for contributing element-plus.

• You can comment with /label Components:[component_name] to add a label for which component you are working on.
• You may join our for staying tuned.

[github-actions]

[github-actions]

Hello @lequangdongg, thank you for contributing to element-plus, please see our guideline to see how to make contribution

[github-actions]

🧪 Playground Preview: https://element-plus.run/?pr=14326
Please comment the example via this playground if needed.