Make usage of the search icon more consistent and meaningful

[snehapatil2001]

issue: #63023

What?

Changed icons to menu for the command part and plus for the Zoom In functionality in the Image block toolbar.

Why?

This PR updates the icons used in the Gutenberg editor to improve visual consistency and clarity. The menu icon is now used for the command part, aligning with standard UI practices for menu interactions. The plus icon replaces the previous icon for Zoom In in the Image block toolbar, making it more intuitive and recognizable for users.

How?

• Updated the ZoomDropdown component in components/image-editor/zoom-dropdown.js to use the plus icon for Zoom.
• Modified the render functions of the Dropdown component to conditionally render the menu and plus icons based on specific states.
• Imported and utilized the icons from the @wordpress/icons library.

Testing Instructions

1. Open a post or page in the Gutenberg editor.
2. Insert an Image block.
3. Verify that the toolbar displays a plus icon for Zoom In in the Image block.
4. Check that the command part of the toolbar now shows a menu icon.
5. Perform Zoom In and Zoom Out actions to ensure the functionality works correctly with the new icons.

Testing Instructions for Keyboard

• Navigate to an Image block using keyboard navigation.
• Ensure that the Zoom In functionality can be accessed and used effectively using keyboard shortcuts or tab navigation.
• Verify that the command part of the toolbar is accessible and labeled correctly for screen readers.

Screenshots or screencast

Screenshots or a screencast demonstrating the updated icons in action would be added here.

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Co-authored-by: snehapatil2001 <snehapatil02@git.wordpress.org>

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