feat: DMS Endpoint `postgres_settings`

[magreenbaum]

Description

Add postgres_settings to aws_dms_endpoint and other additional arguments added after v5.

Motivation and Context

• https://github.com/hashicorp/terraform-provider-aws/issues/34724
• https://github.com/hashicorp/terraform-provider-aws/issues/29470
• https://github.com/hashicorp/terraform-provider-aws/issues/34316
• https://github.com/hashicorp/terraform-provider-aws/issues/33778
• https://github.com/hashicorp/terraform-provider-aws/issues/33158

Breaking Changes

No.

How Has This Been Tested?

• [x] I have updated at least one of the examples/* to demonstrate and validate my change(s)
• [x] I have tested and validated these changes using one or more of the provided examples/* projects
• [x] I have executed pre-commit run -a on my pull request

[antonbabenko]

This PR is included in version 2.1.0 :tada:

[github-actions[bot]]

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