rpc: verify address is for correct net

Verify that the addresses we're decoding when sending coins onchain are
for the correct network. Without this check we'll convert the users
addresses to their equivalent on other networks, which is a gross
violation of the principle of least astonishment.

docs/release-notes/release-notes-0.17.0.md

@@ -72,6 +72,9 @@ package](https://github.com/lightningnetwork/lnd/pull/7356)
   `grpc.keepalive_time_ms=5100` is recommended on the client side (adding 100ms
   to account for slightly different clock speeds).
 
+* [Fixed a bug where we didn't check for correct networks when submitting
+  onchain transactions](https://github.com/lightningnetwork/lnd/pull/6448).
+
 ## Misc
 
 * [Generate default macaroons