It was previously wrongly verifying the input in its URL encoded format
when setting the hostname component with curl_url_set(), so it wrongly
rejected '%'.
Now it URL decodes the name appropriately before the check.
Added tests to lib1560 to verify that a fine %-code is okay and that a
bad %-code (that decodes to '%') is rejected.
Regression from 0a0c9b6dfa, shipped in 8.0.0
Fixes#14656
Reported-by: Venkat Krishna R
Closes#14657