feat: use symfony/deprecation-contracts to report deprecations

[alexislefebvre]

Fixes GH-665.

Sources:

• 4.7.0: enable deprecations (previously commented) #608
• 4.5.1: Support Symfony 6 #603
• 4.2.0: Create WebTestCase::loginClient to allow working with a single kernel #567

For testing the deprecations: https://symfony.com/doc/8.0/components/phpunit_bridge.html#write-assertions-about-deprecations

[alexislefebvre]

This method is called by other methods:

LiipFunctionalTestBundle/CHANGELOG.md

Lines 20 to 26 in 8c91766

	Deprecated the following methods, use [loginUser() from Symfony 5.1+](https://symfony.com/doc/5.4/testing.html#logging-in-users-authentication) instead of:
	- `makeClient`
	- `makeAuthenticatedClient`
	- `makeClientWithCredentials`
	- `loginAs`
	- `loginClient`
	- `createClientWithParams`

I’m not sure that __METHOD__ returned this method or the method that called it.

TODO: check it. And if necessary, add deprecations to the caller methods.

[alexislefebvre]

Current code and symfony/deprecation-contracts use silented deprecations, that are not reported by PHPUnit.

Maybe we should just remove @ from current deprecations.