Add Swap_Rejected state to allow for database pruning

```
$ lighting-cli peerswap-swap-out 100000 HIDDENxHIDDENx0 lbtc
{
"code": -1,
"message": "swap canceled, reason: unknown"

local log ...
2022-04-22T06:49:13.236Z INFO plugin-peerswap-plugin: [Swap:5e0732e795a884dff96027ffd59e12d6f0f6f4e34e453b5b2da07df8e6e8cc8b] Start new swap of type swap out: peer: HIDDEN chanId: HIDDENxHIDDENx0 initiator: HIDDEN amount 100000
```

- [x] If the swap is immediately rejected the console should say why it was rejected.
- [x] The log should print the rejection and reason.
- [x] Please simplify log prefix to "Start swap out" and equivalent for "Start swap in"

```
remote log ...
Apr 22 06:49:13 lightning-charge-production-hwwp docker[222795]: 2022-04-22T06:49:13.502Z INFO plugin-peerswap-plugin: [FSM] Action failure peer not allowed to request swaps
```

- [x] Please add the rejected peer's pubkey to this log entry.

The following allows for safely removing database entries that did not result in a corresponding database entry on the peer. This would allow for frequent swap attempts without bloating database storage with rejected swap attempts.
- [ ] Add another terminal state that can come directly from SendRequest called "State_SwapRejected" distinct from "State_SwapCanceled".
- [ ] Prune Swap_Rejected entries after it is clear the rejection happened.
- [ ] Rename cancel messages to reject messages in the code so they are more distinct from the separate cancel path.