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.Core/CoreConfig.cs

@@ -1,3 +1,5 @@
+using Serilog.Events;
+
 namespace PluralKit.Core
 {
     public class CoreConfig
@@ -7,5 +9,8 @@ namespace PluralKit.Core
         public string InfluxUrl { get; set; }
         public string InfluxDb { get; set; }
         public string LogDir { get; set; }
+
+        public LogEventLevel ConsoleLogLevel { get; set; } = LogEventLevel.Verbose;
+        public LogEventLevel FileLogLevel { get; set; } = LogEventLevel.Information;
     }
 }