Scaffolding refactor

[ilgooz]

• Consider moving to a better template engine
• Remove placeholders
• Create an API for Ignite apps to access scaffolding features, sample use case: say there is an app wants to scaffold ibc modules but they need to access to generic module scaffolding features to not duplicate work.

@toschdev has mentioned that;

Can we still maintain a message "Chain scaffolded with Ignite CLI"?
Because current placeholders kind of serve as this message and would be a shame when it's entirely gone.