Sidebar, icons, adjustments and fixes

Fixes

• Adjusted action buttons' icons in the sidebar
• Adjusted the corner radius of downloads panel items to match the download manager in AI Dev Gallery
• Adjusted the text inside the identity panel
• Fixed simple tab transitions JS script causing the web content to be invisible when first launching Firefox
• Fixed some panel headers using the incorrect font weight and color
• Fixed the browser UI being visible in full screened videos if vertical tabs are enabled
• Fixed wonky inPrivate window downloads notice
• Progress styling side panel and vertical tabs
• Restored autoscroller
• Removed logging from tab transitions JS scripts

Removals

• Removed icon spacing from identity panel clear site data button