Support using api key to connect selfhosted Elasticsearch

[yp05327]

🐛 Describe the bug

mem0/mem0/vector_stores/elasticsearch.py

Lines 28 to 40 in e4e5511

	# Initialize Elasticsearch client
	if config.cloud_id:
	self.client = Elasticsearch(
	cloud_id=config.cloud_id,
	api_key=config.api_key,
	verify_certs=config.verify_certs,
	)
	else:
	self.client = Elasticsearch(
	hosts=[f"{config.host}" if config.port is None else f"{config.host}:{config.port}"],
	basic_auth=(config.user, config.password) if (config.user and config.password) else None,
	verify_certs=config.verify_certs,
	)

The initialize of Elasticsearch only support using api key to connect to the cloud service.
For the selfhosted instance, I can also use api_key to connect it. So api_key should also be provided in L37-L39.

[yp05327]

This is a sample to fix this issue: yp05327@ab9940c