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/Autoproxy.cs

@@ -11,9 +11,9 @@ namespace PluralKit.Bot
 {
     public class Autoproxy
     {
-        private readonly DbConnectionFactory _db;
+        private readonly Database _db;
 
-        public Autoproxy(DbConnectionFactory db)
+        public Autoproxy(Database db)
         {
             _db = db;
         }