Switching the xml.server.preferBinary value should restart the server

[fbricon]

When running a JVM and setting xml.server.preferBinary=true, I expect the XML LS to restart with in binary mode, or at the very least having a popup telling me to restart vscode, so the new settings can be applied.

[GitMensch]

I guess this could be added easily with inspecting the old and new setting, then executing xml.restart.language.server from #551.

[GitMensch]

With #551 being shipped with version 0.22.0 it should be much easier to do this without restarting vscode altogether - still when changing xml.server.preferBinary the command should be executed automatically.

[GitMensch]

friendly ping