chainreg: update tapoort node awareness to account for bitcoind 19+

Bitcoind 23 will use the new `getdeploymentinfo` while versions after 19
(but below 23) will use the `UnifiedSoftForks` field instead of the
`SoftForks UnifiedSoftForks` field.

With this PR the taproot gating logic has been tested on bitcoind
versions: 21, 22, and 23. 21 is when the taproot logic was first added.

docs/release-notes/release-notes-0.15.1.md

@@ -30,7 +30,9 @@ of the draft BIP.
 ## Taproot
 
 [`lnd` will now refuse to start if it detects the full node backend does not
-support Tapoot](https://github.com/lightningnetwork/lnd/pull/6798).
+support Tapoot](https://github.com/lightningnetwork/lnd/pull/6798). [With this
+change](https://github.com/lightningnetwork/lnd/pull/6826), the officially
+supported versions of bitcoind are: 21, 22, and 23.
 
 [`lnd` will now use taproot addresses for co-op closes if the remote peer
 supports the feature.](https://github.com/lightningnetwork/lnd/pull/6633)