Add ability to access Slimproto settings

[Slim1399]

Hi,
Why do we not have access to the local Slimproto interface of player provider ? This is necessary to adjust the latency of Bluetooth speakers synchronized with wired systems.

[OzGav]

Lack of time. I can change this to a feature request unless you are able to submit a PR.

[Slim1399]

If i could i had already done it. Sorry !