[Sets] Deprecate ComposerTriggeredSet in favor of ComposerPackageConstraintInterface

[TomasVotruba]

ComposerPackageConstraintInterface from #7877 turned out to replace ComposerTriggeredSet outright, not just complement it, so the class is now marked deprecated.

/**
 * @deprecated Bond the rules themselves instead, by implementing the ComposerPackageConstraintInterface. A set
 * triggered on a single major version has to be repeated for every version an upgrade passes through, while a bonded
 * rule states the exact package version its target API is available from and applies from there upwards.
 *
 * @see \Rector\VersionBonding\Contract\ComposerPackageConstraintInterface
 */
final readonly class ComposerTriggeredSet implements SetInterface

The comparison table in #7877 framed the triggered set as the tool for upgrade paths — one set per version jump. In practice that is the weakness: a project going from PHPUnit 6 to 12 had to pick up six sets in order, and every rule had to be repeated in each of them to survive a direct jump. A bonded rule needs none of that:

public function provideComposerPackageConstraint(): ComposerPackageConstraint
{
    // createMock() was added in PHPUnit 5.4, so this applies to 5.4 and everything after
    return new ComposerPackageConstraint('phpunit/phpunit', '>=5.4');
}

It is also more precise than ^ matching allows — >=12.0.3, >=13.2, or >=8.4 <10.0 for an API that was later removed.

Both extensions have moved:

• [Sets] Drop per-version composer-triggered sets already covered by composer-based set rector-symfony#1010 — 208 triggered sets removed, all covered by the composer-based set
• [Sets] Drop the PHPUnit 12.0, 12.5 and 13.0 triggered sets covered by composer-based rector-phpunit#757 and Fix wrong docs for ArgumentRemoverRector #758 — every per-version rule bonded, no triggered set left

Twig is the last user, through TwigSetProvider. So the class keeps working, and the internal resolving in SetManager and SetProviderCollector is ignored in phpstan.neon rather than rewritten, until that one moves over too.

The rest of the set object machinery goes with it

A set described as an object only ever existed so it could be matched against the installed packages. Once the rules carry that information themselves, a plain set file is enough, so these are deprecated too:

• SetInterface and Set
• SetProviderInterface, SetManager, SetProviderCollector
• CoreSetProvider and PHPSetProvider

Every note links back to this PR, so anyone hitting the deprecation in an IDE can read the reasoning here.

Nothing is removed and nothing changes at runtime — the sets are still served from these classes, so their internal use is ignored in phpstan.neon rather than rewritten.

Green: 5373 tests, PHPStan and ECS clean.