Make Importer Interceptable in ImporterFactory

[abiverderci]

Jh\Import\Import\ImporterFactory::create() returns new Importer(...) directly. Because the object is not created through the object manager, Magento never substitutes an Importer\Interceptor, so any plugin declared against Jh\Import\Import\Importer is silently inert.

Additional note: the $indexer argument also news its value and the $progress argument is also resolved at runtime via a progressFactory->get() - not carrying this over (ie, letting di handle the injection here) may cause regressions

Suggested Fix

Create Importer through the object manager inside ImporterFactory::create() rather than with new, ensuring runtime arguments remain consistent

Risks

• Any consuming project that declared a plugin on Importer and never realised it was inert would have that plugin start firing on upgrade, with no code change on their side.

Acceptance Criteria

• A plugin declared against Jh\Import\Import\Importer::process() fires for a real import run.
• setup:di:compile generates an Importer interceptor.
• Indexer and the progress implementation are still supplied by ImporterFactory, not by DI, and are covered by a test that fails if either is dropped.
• Existing import behaviour is unchanged when no plugin is declared.