htlcswitch: log link message with channel point

In lnd, log messages about channels are generally logged with a
reference to their channel point rather than the short channel id.
Channel point is reorg-resistant and also easier to look up in for
example a block explorer.

In the link however, all log messages are accompanied by short channel
id. This makes it difficult to grep a log for all channel activity. The
PEER message for example which are often crucial to analyse, are logged
with channel points.

This commit modifies the link logging to also use channel points.

docs/release-notes/release-notes-0.14.0.md

@@ -114,6 +114,8 @@ you.
 
 * [Missing dots in cmd interface](https://github.com/lightningnetwork/lnd/pull/5535).
 
+* [Link channel point logging](https://github.com/lightningnetwork/lnd/pull/5508)
+
 ## Database
 
 * [Ensure single writer for legacy