Is your feature request related to a problem? Please describe.
During development, I want to have modularity for the files I am working on, so mj-include solves the problem. In production, the mjml files will be passed through the templating system first, because depending on the conditionals within the template, the number of columns might change, which will result in the html being rendered to be different. The mjml will then be passed to a mjml rendering server, which will return the rendered html.

Describe the solution you'd like
I would like to be able to "flatten" all my mjml files when deploying for production, but not render to html, perhaps via a configuration option in the mjml cli. The reason for this is that the mjml has to pass through the template engine first. In addition, I want the mjml rendering server to be stateless for ease of deployment (everything else is written in Go). The rendering process in production would look like:

• flattened mjml file is loaded and populated by the template engine
• the result is then sent to a mjml rendering server
• the html result is sent back

Describe alternatives you've considered
None.

Additional context
None.