[symfony] Add PreferClassServiceReferenceRule for config closures

[TomasVotruba]

Adds PreferClassServiceReferenceRule (Symfony PHP config closures), plus its two collectors.

When a config closure points a string service id at a class:

$services->alias('some.helper', SomeHelper::class);

then a service('some.helper') reference names the very same service the class does. The rule asks for service(SomeHelper::class) instead, so the reference carries the type. Once every reference names the class, the string alias nothing else asks for can be dropped.

Implementation:

• ClassTargetServiceAliasCollector collects alias('id', X::class) pairs,
• ServiceStringReferenceCollector collects service('id') string references,
• the rule cross-references the two over a CollectedDataNode and reports each string reference an alias already covers with a class.

A service(X::class) reference and a service('id') no alias covers are left alone.

Registered in config/symfony-config-rules.neon (rule + both collectors), covered by a RuleTestCase with config-closure fixtures.

Green locally: ECS, PHPStan, Rector, composer-dependency-analyser, neon-lint, tests.