Handle required project for a tutorial in a better way

[ericrosenbaum]

Currently the "Animate an Adventure Game" tutorial requires content available in a specific project.

Current we use a hack to check the URL ID, and if you are not already on the project, load it in a new tab with the project and tutorial open:

5314426

For now we will just fix the URL so that it works in production.

Note: also think about what to do in Scratch Desktop- probably just hide this tutorial from the library.

[thisandagain]

/cc @cwillisf We'll need to hide this tutorial in Scratch Desktop.