Added ExporterInterface usage instead of Exporter class

[pkameisha]

Subject

I am targeting this branch, because {reason}.

Closes #{put_issue_number_here}.

Changelog

### Added
- Added usage of ExporterInterface instead of Exporter class.

### Changed
- Drop support sonata-project/exporter 2.x.

[VincentLanglet]

I think some change here:
https://github.com/sonata-project/exporter/blob/3.x/src/Bridge/Symfony/Resources/config/services.php#L64-L67
will be needed too.

See an example here:

SonataAdminBundle/src/Resources/config/core.php

Lines 152 to 157 in 6dcebd2

	->set('sonata.admin.request.fetcher', AdminFetcher::class)
	->args([
	new ReferenceConfigurator('sonata.admin.pool'),
	])
	->alias(AdminFetcherInterface::class, 'sonata.admin.request.fetcher')

So I think we'll need something like

$services->alias(ExporterInterface::class, 'sonata.exporter.exporter');

[VincentLanglet]

explorer 3.1.1 is released, you can take a new try

[pkameisha]

explorer 3.1.1 is released, you can take a new try

done. I think, it should work now

[VincentLanglet]

Suggested change

	"sonata-project/exporter": "^3.1",
	"sonata-project/exporter": "^2.14 || ^3.1.1",

We need to keep the v2 support for the PHP 7.4 support.
I added the Interface on the v2 of exporter because it was simpler.

[pkameisha]

agree, v2 is added

[VincentLanglet]

Thanks