Add webroot delay

[osirisinferi]

Fixes #9643.

Not sure if the documentation needs to be updated. I don't think this option will be used very often.

Pull Request Checklist

• The Certbot team has recently expressed interest in reviewing a PR for this. If not, this PR may be closed due our limited resources and need to prioritize how we spend them.
• If the change being made is to a distributed component, edit the master section of certbot/CHANGELOG.md to include a description of the change being made.
• Add or update any documentation as needed to support the changes in this PR.

[alexzorin]

Thanks. I'm not so sure whether this feature is worth adding.

I don't think the use case discussed in #9643 warrants the change or that Certbot should go out of its way to cater to such setups.

Tomcat might justify things, but it's probably single/double-digit users and there's a relatively straightforward server.xml workaround. I think the realer problem with Tomcat is the lack of good documentation about how to use it with Certbot.

The only thing in favor of this flag is that it's simple.

[osirisinferi]

I'm not so sure whether this feature is worth adding.

I can understand that, use case probably isn't large indeed, I won't feel offended if you'd close this PR. 😛 But as the issue wasn't closed as "won't fix", I thought I'd just throw the PR together anyway 🙂