cli-config.php compatibility with DBAL

[PowerKiKi]

Since DBAL 2.11.0 and doctrine/dbal#3956, it is now deprecated to use HelperSet in cli-config.php. This will become impossible in DBAL 3, following doctrine/dbal#4059.

This means that, in order to keep sharing a single config file for both packages, this package should also accept the new \Doctrine\DBAL\Tools\Console\ConnectionProvider. It could actually be a new interface along the lines of:

namespace \Doctrine\ORM\Tools\Console;

interface EntityManagerProvider
    public function getEntityManager(string $name) : EntityManagerInterface;
}

I suppose the support of HelperSet could be drop entirely in the next major version too. So long we can use a HelperSetManagerProvider that extends the EntityManagerProvider.

All commands must be adjusted to access the entity manager from a provider instead of the HelperSet. Deprecation messages when using HelperSet must be thrown appropriately.

See related doctrine/migrations#1070

[beberlei]

I have updated the description of the issue to explain my approach to performing this deprecation:

1. Introduce EntityManagerProvider as mentioned
2. Introduce a HelperSetManagerProvider that is used and introduced for the deprecated legacy case in ConsoleRunner
3. Introduce AbstractEntityManagerCommand that each command implements. Provide backwards compatibility with other packages extending Doctrine commands.

[beberlei]

Merged #8524 into 2.9.x