Add support for custom domain names on the es endpoint

[Konig-Corey]

Looks like aws supports custom domain names now, would love to add that support.

AWS Post about support
https://aws.amazon.com/about-aws/whats-new/2020/11/amazon-elasticsearch-service-now-supports-defining-a-custom-name-for-your-domain-endpoint/

[lgallard]

@Konig-Corey there're a couple of tickets currently open regarding this new feature:

• AWS ElasticSearch Custom endpoint support
• r/aws_elasticsearch_domain: Add custom endpoint support

As soon as it's available in the AWS provider I can include it in the module.

[dmytro-dorofeiev]

Hi, it seems this feature is already supported by aws provider. Could you please update the module?

[lgallard]

@dmytro-dorofeiev I'll take a look at the resource and make the needed changes that applies.

[lgallard]

@dmytro-dorofeiev @Konig-Corey this feature was included in the lasted release. Just include a block as follows:

  domain_endpoint_options = {
    enforce_https                   = true
    custom_endpoint_enabled         = true
    custom_endpoint                 = "lgallardo.com"
    custom_endpoint_certificate_arn = "arn:aws:acm:us-east-1:123456789101:certificate/abcd1234-ef11-abcd-1234-abcd1234efef"
  }

I updated the advanced_security_options_* in the examples folder as well.