HaishinKit.RTMPSocket.Error should be expoused, so a better UI handling is possible

[peterpaulis]

Currently HaishinKit.RTMPSocket.Error is not accessible due to internal protection, so good UI handling of the error is not possible
like with the case connectionNotEstablished(_ error: NWError?) you cannot access the NWError

change to public would solve this

public final actor RTMPSocket {
    static let defaultWindowSizeC = Int(UInt8.max)

    public enum Error: Swift.Error {
        case invalidState
        case endOfStream
        case connectionTimedOut
        case connectionNotEstablished(_ error: NWError?)
    }