WIP [1181] Expose low level elasticsearch client params
- replace elasticsearch_host and elasticsearch_port with elasticsearch_url
- Add support for AWS Elasticsearch Service
- created universal gitlab elasticsearch client
- add ability to sign requests with aws_signers_v4
- expose elasticsearch_aws_region param
- expose elasticsearch_aws_access_key param
- expose elasticsearch_aws_secret_access_key param
- If using AWS instance credentials they will automatically be picked up by client
- Add support for AWS Elasticsearch Service
Closes #1181 (closed)