Add priority providers

[nicolapalavecino]

Description

Adds the following features:

• Gives the possibility for $noOrder (which externally will be named as prioritized middlewares) to provide any entity required for the next middlewares to execute. Of course the only $noOrder middleware known at the time is the schema validator which does not provide any entity. However, this allows a dev to hoist any priority middleware to have a better control over the order of the middlewares.
• Adds a prioritize decorator that will hoist that middleware as much as it cans. These prioritized middlewares will be executed before any async middleware but always after the schema validator

Test impact

This should be a backward compatible change since the order middleware converter will give the possibilities for middlewares having the $noOrder decorator to provide entities. This is only adding functionality, not removing nor replacing the way middlewares are ordered, it only makes the disposition of middlewares more lax.

[nicolapalavecino]

closed in favor of #16. This PR has a low level control of ordering that we don't want to implement