chore(ui): update react scripts v5

Description

The current version of react-scripts@4 has a lot of vulnerabilities, so this MR updates the package to version 5. It is expected that the update will reduce the number of them.

Side updates:

• updated react-markdown from 4 to 8, fixed compatibility, doesn't work with webpack@5 inside react-scripts@5
• replaced jsonwebtoken with jwt-decode, doesn't work with webpack@5 inside react-scripts@5
• replaced timeago.js with date-fns, fixed compatibility, doesn't work with webpack@5 inside react-scripts@5

Checklist

• MR description has been reviewed
• MR changes are functionally tested
• MR does NOT have text changes OR there are text changes and they have been reviewed
• MR does NOT have API/CLI changes OR there are API/CLI changes and they have been reviewed
• MR does NOT have UI changes OR there are UI changes and they have been reviewed