[AltServer] Moves core ConnectionManager logic to AltKit

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.

AltServer/Connections/ALTWiredConnection+Private.h

@@ -14,6 +14,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 @interface ALTWiredConnection ()
 
+@property (nonatomic, readwrite, getter=isConnected) BOOL connected;
+
 @property (nonatomic, readonly) idevice_connection_t connection;
 
 - (instancetype)initWithDevice:(ALTDevice *)device connection:(idevice_connection_t)connection;