build: Append commit hash to the main LND context

It can be disabled via the new `logging.no-commit-hash` config option.

sample-lnd.conf

@@ -994,6 +994,11 @@
 
 [logging]
 
+; Whether to exclude the current build's commit hash from log lines. Note that
+; the commit hash will not currently show up in all LND log lines as this new
+; feature will take a few versions to propagate through the codebase.
+; logging.no-commit-hash=false
+
 ; Disable logging to stdout and stderror.
 ; logging.console.disable=false