Support `replace_triggers_external_values` in `azapi_resource_action`-resource

Changing certain Azure PostgreSQL server parameters requires a restart of the server.

We are currently using a `azapi_resource_action`-resource to trigger the „restart“ action, however we can’t add the parameter value as a replacement trigger to the resource. As a workaround, we therefore currently have to create a separate `terraform_data`-resource with the relevant values as input and then use `lifecycle.replace_triggered_by` on the `azapi_resource_action`-resource to trigger the replacement.

To simplify this setup, it would be great to have the `replace_triggers_external_values` field, which already exists for the `azapi_resource`-resource, on the `azapi_resource_action`-resource as well.

Start by locating the azapi_resource_action resource implementation and compare its schema and replacement behavior with the existing azapi_resource support for replace_triggers_external_values. Confirm the expected Terraform behavior for external value changes, then add coverage showing that the action resource accepts the field and is replaced when those values change.

Written by the indexing model from the issue text.