Support for Resource Principal Authentication in OCI Plugin

Overview:

Hi team,

Thank you for the work on this plugin — it’s been very helpful in our OCI automation workflows.

I noticed that while the plugin currently supports instance principals for authentication, it does not appear to support resource principals. This limits its usage in certain native OCI environments where instance principal access is not viable or preferred.

Would it be possible to consider adding support for resource principal authentication(ResourcePrincipalConfigurationProvider), similar to how instance principals are handled?

Use Case:
We are trying to run Packer builds from an OCI Function(eg - OCI Devops), which only has access via a resource principal. Without support for resource principals, we are unable to authenticate properly from these environments.

Expected Behavior:
When run from a resource principal-enabled environment, the plugin should automatically authenticate using the resource principal similar to the current instance principal support.

Current Behavior:
Attempting to authenticate without providing a config file or using instance principal results in a failure.

Reference:
Resource principal configuration should be something similar to - https://github.com/hashicorp/packer-plugin-oracle/blob/main/builder/oci/config.go#L226