Move system updates to the same patch system as members

PluralKit.Core/Models/Patch/ModelPatchExt.cs

@@ -0,0 +1,31 @@
+using System.Threading.Tasks;
+
+using Dapper;
+
+namespace PluralKit.Core
+{
+    public static class ModelPatchExt
+    {
+        public static Task<PKSystem> UpdateSystem(this IPKConnection conn, SystemId id, SystemPatch patch)
+        {
+            var (query, pms) = patch.Apply(new UpdateQueryBuilder("systems", "id = @id"))
+                .WithConstant("id", id)
+                .Build("returning *");
+            return conn.QueryFirstAsync<PKSystem>(query, pms);
+        }
+
+        public static Task DeleteSystem(this IPKConnection conn, SystemId id) =>
+            conn.ExecuteAsync("delete from systems where id = @Id", new {Id = id});
+        
+        public static Task<PKMember> UpdateMember(this IPKConnection conn, MemberId id, MemberPatch patch)
+        {
+            var (query, pms) = patch.Apply(new UpdateQueryBuilder("members", "id = @id"))
+                .WithConstant("id", id)
+                .Build("returning *");
+            return conn.QueryFirstAsync<PKMember>(query, pms);
+        }
+        
+        public static Task DeleteMember(this IPKConnection conn, MemberId id) =>
+            conn.ExecuteAsync("delete from members where id = @Id", new {Id = id});
+    }
+}