Splice Reestablish Flow Question

Question of reestablish and `tx_abort`.

We two nodes, l1 and l2 who are doing an interactive splice. Both sides have sent `tx_complete` and the splice has reached the signing phase.

By signature ordering rules, l2 signs first.

```
l1                           l2
       <- commit_sig
         *l1 restarts*
```

Nodes reconnect and reestablish flow begins. l1 has dropped the splice candidate as it never got to signing and l2 kept it as it.

```
l1                           l2
       <- channel_reestablish (w/splice txid)
          tx_abort ->
       <- tx_abort
```

l1 is aborting for this reason: `We are initiating tx_abort for reason: next_funding_txid not recognized. Sending tx_abort.`

# Here is the question

Under CLN's behavior, we would always restart the channel flow from the very begining. This means another `channel_reestablish` message along with the rest of the normal new connection flow.

Under Eclair's behavior, `tx_abort` continues the channel in place and no new `channel_reestablish` message is sent.

Switching CLN to Eclair's behavior we new abort the reestablish and the rest of the reestablish flow is simply aborted. This is showing up in tests because `channel_ready` is no longer firing.

This raises a larger question though of it is safe to `tx_abort` mid-reestablish given the complex nature of a reestablish and how this might effect other things that depending on it be performed precisely -- including future reestablish needs that may arise.

I believe special casing our `resume_splice_negotiation` with this logic may address the issue:
```
	/* If `recv_commitments` true and msg_received `tx_abort`:
	 *   - If !have_i_signed_inflight()
	 *     - DROP inflight on master
	 *     - If this is during a reestablish:
	 *       - send tx_abort and return
	 *     - otherwise
	 *       - go into check_tx_abort flow
	 *   - otherwise
	 *     - We have sent a sig and we cannot drop inflight
	 *     - If this is during a reestablish:
	 *       - send tx_abort and return
	 *     - otherwise
	 *       - go into check_tx_abort flow
	 */
```