Scan page UX improvements

[asafgabai]

• The look of the spinner while the scanning is in progress, makes it feel like the user can run multiple scans in parallel. The user also gets the feeling that the process might be stuck. Adding a progress bar (not necessarily an accurate one) or showing the current stage in the scanning process was suggested.
• Show more than one impact path in each vulnerability (if exist). In Xray UI, there's a drop-down list of the impact paths to choose which of them to view.
• Show JFrog Research information. We already get it from Xray, but we need to add it to the results' view.
• Add a header below the "JFrog Xray" title. It's meant to help users understand what the extension does. It can be found in other extensions too.
• Avoid clearing the results when moving from the scan page to another page and then returning to the scan page. Users don't always expect that, and then they need to run the scan again.