Add documentation for new Windows PV tools

[dinhngtu]

Add instructions for using XenClean and XenBootFix to the troubleshooting guide.
Also remove outdated WPV 8.2 instructions.

I'll keep this PR as draft until there's a fully signed version of the new Windows PV drivers.

Before submitting the pull request, you must agree with the following statements by checking both boxes with a 'x'.

• "I accept that my contribution is placed under the CC BY-SA 2.0 license [1]."
• "My contribution complies with the Developer Certificate of Origin [2]."

[1] https://creativecommons.org/licenses/by-sa/2.0/
[2] https://docs.xcp-ng.org/project/contributing/#developer-certificate-of-origin-dco