Add package for AsyncSocket

AsyncSocket is an asynchronous TCP/IP socket networking library. It's used in MPExtended for the connection with WifiRemote, which runs inside MP. There's currently no package available on NuGet, so I hope it's fine to upload them here.

One remark though: the shipped binary is named Deusty.Net.dll, while the package is named AsyncSocket. I can rename the package, but it's a lot less descriptive imo. What's your opinion?