Too many refactors in one:

- Allowed adding ephemeral(ish) views and functions
- Moved message_count to a concrete database field
- Moved most proxy logic to a stored procedure
- Moved database files around and refactored schema manager

PluralKit.Bot/Lists/PKListMember.cs

@@ -6,7 +6,6 @@ namespace PluralKit.Bot
 {
     public class PKListMember: PKMember
     {
-        public int MessageCount { get; set; }
         public ulong? LastMessage { get; set; }
         public Instant? LastSwitchTime { get; set; }
     }