chore: move crates into crates/ dir (#1958)

I'd like to tidy up the root a little, and it's nice to have all the
rust crates in one place

crates/atuin-server-postgres/migrations/20230515221038_trigger-delete-only.sql

@@ -0,0 +1,30 @@
+-- We do not need to run the trigger on deletes, as the only time we are deleting history is when the user
+-- has already been deleted
+-- This actually slows down deleting all the history a good bit!
+
+create or replace function user_history_count()
+returns trigger as 
+$func$
+begin
+	if (TG_OP='INSERT') then
+		update total_history_count_user set total = total + 1 where user_id = new.user_id;
+
+		if not found then
+			insert into total_history_count_user(user_id, total) 
+			values (
+				new.user_id, 
+				(select count(1) from history where user_id = new.user_id)
+			);
+		end if;
+	end if;
+
+	return NEW; -- this is actually ignored for an after trigger, but oh well
+end;
+$func$
+language plpgsql volatile -- pldfplplpflh
+cost 100; -- default value
+
+create or replace trigger tg_user_history_count 
+	after insert on history 
+	for each row 
+	execute procedure user_history_count();