Deprecate FilterInterface::filter method

[VincentLanglet]

Subject

I am targeting this branch, because BC.

This method is not used in SonataAdmin so we don't have to require this signature in our Interface.

Persistence bundle are done this way:

abstract class Filter extends BaseFilter
{
    /**
     * @var bool
     */
    protected $active = false;

    public function apply($queryBuilder, $value)
    {
        $this->value = $value;
        if (\is_array($value) && \array_key_exists('value', $value)) {
            list($alias, $field) = $this->association($queryBuilder, $value);

            $this->filter($queryBuilder, $alias, $field, $value);
        }
    }

They just have to add

abstract function filter(...)

With specific signature. ($alias is only useful for ORM bundle for instance)

Closes #6269.

Changelog

### Deprecated
- Deprecate `FilterInterface::filter()` method