Several more database-y refactors

- DbConnectionFactory renamed to "Database", will now be the primary entry point for DB stuff
- Created IPKConnection interface mostly containing async extensions to IDbConnection, use this going forward
- Reworked the Connection/Command wrappers (that have performance/logging extensions)
- Probably more stuff that I forgot???

PluralKit.Bot/Commands/ServerConfig.cs

@@ -13,9 +13,9 @@ namespace PluralKit.Bot
 {
     public class ServerConfig
     {
-        private DbConnectionFactory _db;
+        private Database _db;
         private LoggerCleanService _cleanService;
-        public ServerConfig(LoggerCleanService cleanService, DbConnectionFactory db)
+        public ServerConfig(LoggerCleanService cleanService, Database db)
         {
             _cleanService = cleanService;
             _db = db;