[DEMO] Refactor message new

[stenolog]

(this should have gone to @ccellado 's repo, accidentally sent here)

Just a cleanup of

• https://github.com/ergoplatform/ergo/pull/2113

to speed review process up.

Created via:

git checkout master
git checkout -b refactor-message-new
git cherry-pick c55fdefdf93
git cherry-pick 810d70805a