Subsystem "web": Expose effective configuration through domain management API

The "configuration" attribute is currently "undefined", but management clients require access to the default values:

[domain@localhost:9999 /] /profile=default/subsystem=web:read-resource(recursive=true)
{
"outcome" => "success",
"result" => {
"configuration" => undefined,
"connector" => {"http" => {
"protocol" => "HTTP/1.1",
"socket-binding" => "http",
"scheme" => "http",
"virtual-server" => undefined,
"ssl" => undefined
}},
"virtual-server" => {"localhost" => {
"alias" => ["example.com"],
"access-log" => undefined,
"rewrite" => undefined
}}
},
"compensating-operation" => undefined
}