* feat: update backend project links
Replace solution and remix Glitch links with equivalent Repl.it links in backend projects/challenges and intro pages.
* fix: link and Repl.it casing
* fix: update mention of glitch in testing challenge
* Apply suggestions from code review
Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>
Co-authored-by: Mrugesh Mohapatra <1884376+raisedadead@users.noreply.github.com>
Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>
