updateUrl

For APIs using the mainUrl in the prefix for MainAPI::load, this function replaces the scheme, host and port from an old link to the new mainUrl.

https://en.wikipedia.org/wiki/Uniform_Resource_Identifier

            userinfo       host      port
            ┌──┴───┐ ┌──────┴──────┐ ┌┴─┐
    https://john.doe@www.example.com:1234/forum/questions/?tag=networking&order=newest#:~:text=whatever
    └─┬─┘   └─────────────┬─────────────┘└───────┬───────┘ └────────────┬────────────┘ └───────┬───────┘
    scheme            authority                path                   query                 fragment