Redesign and restructure UI for better user experience.

• Keeping track of progress with a progress bar
• Enhancing overall usability
• Enhance switching collections in sidebar
• Add feature for editing Main.yaml attributes: Name, Collector/s, XPATH recommendation, Description

See Mockups here: https://www.figma.com/design/v4xEGGJDEKjv6EmdkRJopH/Import?node-id=0-1&t=0AWKxf0I3WF6chNR-1