Hardcoded url

[Nishthajain7]

Issue:

Fixes #3910

Changes:

Use the EDITOR_URL environment variable to construct the callback URL. instead of hardcoded https://editor.p5js.org/auth/google/callback

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• has no typecheck errors (npm run typecheck)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #123
• meets the standards outlined in the accessibility guidelines

[Nishthajain7]

Thank you for noticing. I checked out from the wrong branch