showStart variant for when there's no worktree file

Clean up some uses of showStart with "" for the file,
or in some cases, a non-filename description string. That would
generate bad json, although none of the commands doing that
supported --json.

Using "" for the file resulted in output like "foo  rest";
now the extra space is eliminated.

This commit was sponsored by Fernando Jimenez on Patreon.

Command/Init.hs

@@ -40,7 +40,7 @@ seek = commandAction . start
 
 start :: InitOptions -> CommandStart
 start os = do
-	showStart "init" (initDesc os)
+	showStart' "init" (Just $ initDesc os)
 	next $ perform os
 
 perform :: InitOptions -> CommandPerform