[Set] Allow a version constraint in ComposerTriggeredSet

[TomasVotruba]

ComposerTriggeredSet hardcodes '^' . $version, so a set can only be bound to a single major version:

return Semver::satisfies($package->getVersion(), '^' . $this->version);

That is fine for the per-version upgrade sets, but it makes it impossible to register a set that applies across majors - such as rector-phpunit's new composer-based.php, which should load for any installed PHPUnit and does its own per-rule version gating via ComposerPackageConstraintInterface and ruleWithConfigurationComposerVersionBound().

A bare version keeps behaving exactly as before; anything that is not a bare version is used as a constraint:

private function resolveVersionConstraint(): string
{
    if (Strings::match($this->version, self::BARE_VERSION_REGEX) !== null) {
        return '^' . $this->version;
    }

    return $this->version;
}

So both of these work:

// unchanged - matches ^10.0
new ComposerTriggeredSet(SetGroup::PHPUNIT, 'phpunit/phpunit', '10.0', __DIR__ . '/../config/sets/phpunit100.php'),

// new - matches any PHPUnit 10 and up
new ComposerTriggeredSet(SetGroup::PHPUNIT, 'phpunit/phpunit', '>=10.0', __DIR__ . '/../config/sets/composer-based.php'),

This is what lets withComposerBased(phpunit: true) pick up a package's composer-based set regardless of which PHPUnit major is installed, without registering the same set once per major version.

Backward compatible - every existing ComposerTriggeredSet in rector-src and the extension packages passes a bare version and keeps the ^ behaviour. Covered by ComposerTriggeredSetTest, including the bare version cases.