Add old GMCP Enabled Script

@iLPdev がすでに取り組んでいます。

2020年7月20日 から。

This is the XML for my old GMCP Enabled script. It's technically more accurate that what is in discMapper currently, because it only runs when the `sysProtocolEnabled` event fires and the protocol is, in fact, GMCP. I'm just too tired ATM to mess with it.

```

<name>dsGMCPEnabled</name>
<packageName></packageName>
<script>function dsGMCPEnabled(_, protocol)
if protocol == "GMCP" then
map.echo(" - GMCP Enabled")
end
end

sysProtocolEnabled

```