Replace `wait_for` with script evaluation about chromic_pdf

[maltoe]

@jarimatti I went ahead and added the evaluate option and rewrote your wait_for option based on a JS script. If you have time to test it out on your wait_for use-case, that would be super nice 🙏

[jarimatti]

This looks nice! I agree, the wait_for has known issues and this feels like a better and much more versatile approach. I will give this a spin.

[jarimatti]

If I'm the only one using wait_for (and not even that much) I'm all in for removing it completely if you think it makes sense. I can easily replace any use of it with the new approach.

[maltoe]

🤷‍♂️ idk if it has more users, @dgigafox perhaps... On the other hand the script ended up being so small that I think I'm fine with maintaining it in the code. At least this way it is tested (in contrast to when I would just use it as an example in the docs).