[Feature Request] Allow to make an display order of module position in config

[bugsounet]

My proposal for #3761

• I use flex box for create region container
• I have moved container definition to main.css (for css tunning, maybe it can be useful)
• I create order in module config for define module order display from position

Advantage:

We don't have to move module config in another place in array of modules

Another advantage that i did'nt think:

We can change dynamicaly module order of a container:

• So, in this case, for a module config builder, (I won't mention the name because otherwise I'll get angry...)
  It can be usefull for a config preview (before saving config)
  --> just change style css order module value for see preview

• Or, change order value in dev console for testing

Disadvantages

I don't see any ;)