Simultaneously updating WiredConnectionHandler.notificationConnections can cause a crash, so we enforce serial access to notificationConnections via DispatchQueue.
Treating AltKit as a full module resulted in more complexity than necessary, when we really just wanted to share some files between different targets. Now we can share individual files across modules as-needed without AltKit overhead.
Refactors ConnectionManager to use arbitrary RequestHandlers and ConnectionHandlers. This allows the core AltServer request logic to be shared across different targets with different connection types.
