Update vault_aws_secret_backend_role to support setting session_tags and external_id

[benashz]

Updates vault_aws_secret_backend_role per: hashicorp/vault#27620

Adds support for setting session_tags and external_id. Which will be
released in vault 1.17.2

Output from acceptance testing:

go tool test2json -t /Users/bash/Library/Caches/JetBrains/IntelliJIdea2024.1/tmp/GoLand/___1TestAccAWSSecretBackendRole_basic_in_github_com_hashicorp_terraform_provider_vault_vault.test -test.v -test.paniconexit0 -test.run ^\QTestAccAWSSecretBackendRole_basic\E$
=== RUN   TestAccAWSSecretBackendRole_basic
--- PASS: TestAccAWSSecretBackendRole_basic (2.44s)
PASS