Add command to delete all switches

PluralKit.Core/Stores.cs

@@ -303,6 +303,11 @@ namespace PluralKit {
         /// </summary>
         Task DeleteSwitch(PKSwitch sw);
 
+        /// <summary>
+        /// Deletes all switches in a given system from the data store.
+        /// </summary>
+        Task DeleteAllSwitches(PKSystem system);
+
         /// <summary>
         /// Gets the total amount of systems in the data store.
         /// </summary>
@@ -416,6 +421,12 @@ namespace PluralKit {
                 return await conn.QueryAsync<ulong>("select uid from accounts where system = @Id", new { Id = system.Id });
         }
 
+        public async Task DeleteAllSwitches(PKSystem system)
+        {
+            using (var conn = await _conn.Obtain())
+                await conn.ExecuteAsync("delete from switches where system = @Id", system);
+        }
+
         public async Task<ulong> GetTotalSystems()
         {
             using (var conn = await _conn.Obtain())