TSK: Improve non-url encoding display

To improve user experience when encoding/decoding string:

[x] In /redirect endpoint, use a regex to determine if you have decoded a valid url or a string
[x] Do not attempt to /redirect when it is not a valid url, and display the string instead
[x] Change argument name in relevant endpoints and return json for clarity
[x] Update README.md to reflect the changes and clarify that encoding/decoding non-url string is possible

atyrode / vite