Allow es domain attributes to be parameterized

[fredliporace]

ES domain creation

Possible difficulty is the use of CDK types, elasticsearch.ElasticsearchVersion.V7_7 for instance. But some useful parameters may be directly defined by **args, such as volume_size, instance_type, etc.

        esd = elasticsearch.Domain(
            self,
            id="cbers2stac",
            # This is the version currently used by localstack
            version=elasticsearch.ElasticsearchVersion.V7_7,
            ebs=elasticsearch.EbsOptions(enabled=True, volume_size=10),
            capacity=elasticsearch.CapacityConfig(
                data_node_instance_type="t2.small.elasticsearch", data_nodes=1,
            ),
        )

Lambda to insert into ES, check environment vars:

            self.create_lambda(
                id="insert_into_elastic_lambda",
                code=aws_lambda.Code.from_asset(path="cbers2stac/elasticsearch"),
                handler="es.create_documents_handler",
                runtime=aws_lambda.Runtime.PYTHON_3_7,
                environment={**self.lambdas_env_,
                             **{"ES_STRIPPED": "YES",
                                "BULK_CALLS": "1",
                                "BULK_SIZE": "10"}},
                layers=[self.layers_["common_layer"]],
                timeout=core.Duration.seconds(30),
                dead_letter_queue=self.queues_["dead_letter_queue"],
                # Concurrent executions tuned to work with t2.small.elasticsearch
                reserved_concurrent_executions=5,
                description="Consume STAC items from queue, inserting into ES",
            )