Update protobufs

[xPaw]

Of note, there's ContentServerDirectory protos along with a new CContentServerDirectory_GetManifestRequestCode_Request message.

Can also use CContentServerDirectory_GetServersForSteamPipe_Response to request servers in a proto format and decode it into something typed here:

SteamKit/SteamKit2/SteamKit2/Steam/WebAPI/ContentServerDirectoryService.cs

Line 81 in 12d90d6

var response = await directory.CallAsync( HttpMethod.Get, "GetServersForSteamPipe", version: 1, args: args ).ConfigureAwait( false );