Fixed server build so that the /lib/donkey folder is cleared first before copying jars over from donkey.

Also moved these steps from the build-server-extensions target into the build-donkey target since they make more sense there.
Issue: MIRTH-2801
MIRTH-2334: Refactored getMetaDataForTree to getMetaDataFromMessage.
Updated Donkey to support multiple servers running on a single database.

On message recovery, only recover messages for the current server.

Made sure that source/destination queues only select messages for the current server.

When reprocessing and replacing a message, the message is now re-assigned to the current server id.
Issue: MIRTH-2792
MIRTH-2803: Modified TcpDispatcher so that it stores a map of connected sockets, keyed by the permutation of local/remote address/port properties. When Keep Connection Open is enabled, discrete sockets and timeout threads are used, so each connection stays open as needed.
MIRTH-2802: Added a Paused initial state to channels.