Add NoteService to handle note operations

NoteService should be the only class with access to NoteDao;
nowhere else should NoteDao be accessed directly.

Channel dependencies are static in PacketProcessor, for now.
Ideally they would be injected in the constructor,
but since the constructor is private and I don't want to open
up that can of worms, I'll leave it like this.
At the very least, now we have a way of injecting services into
the handlers. This will make further restructuring way easier.

src/main/java/tools/DatabaseConnection.java

@@ -3,7 +3,7 @@ package tools;
 import com.zaxxer.hikari.HikariConfig;
 import com.zaxxer.hikari.HikariDataSource;
 import config.YamlConfig;
-import database.NoteRowMapper;
+import database.note.NoteRowMapper;
 import org.jdbi.v3.core.Handle;
 import org.jdbi.v3.core.Jdbi;
 import org.slf4j.Logger;