Function createDmRelayPool

createDmRelayPool(pool: ApplesaucePool, tiers: RelayTiers): DmRelayPool
The relay pool a messaging backend reads and writes through, satisfying kehto's DmRelayPool over the same shared applesauce pool.
Parameters
- pool: ApplesaucePool
  The shared applesauce pool.
- tiers: RelayTiers
  Relay tiers used when a caller names no relays.
Returns DmRelayPool
A DmRelayPool.
Example
```
const dmPool = createDmRelayPool(pool, tiers);
const history = await dmPool.query([{ kinds: [1059], '#p': [me] }]);
```