fix(toolbar): update bookmark menu arrows, icons, and fix scroll issue

[QuietRobot]

Summary of Changes

This PR improves the Bookmarks toolbar menu layout and resolves navigation issues:

• Icon scroll fix: Corrects alignment and position issues when scrolling icons horizontally.
• Arrow clipping fix: Resolves styling so navigation arrows are no longer cut off at the edges.
• Duplicate arrows fix: Removes duplicate arrows from menu items so only one is displayed, maintaining the alignment and size of other menus.
• Updated icons: Adds new vector icons for the up and down arrow indicators.

[Lockframe]

Hello, thank you for the pull request.
Please make sure the icons are 16x16 so that they do not need to be manually resized when used with list-style-image or content

[QuietRobot]

Thanks @Lockframe , I didn't know that.
(my first pull request 😬, I hope I haven't made many mistakes)