Support for IAM Role Chaining

[t0yv0]

The upstream feature hashicorp/terraform-provider-aws#22728 had to be backed out from the pulumi-aws (see #4458) since it introduces a breaking type change to the provider configuration, assumeRole becomes assumeRoles and the type changes from a single object to multiple. Per our backwards compatibility policy, pulumi-aws cannot ship this change as-is until the next major release. This feature is therefore unavailable.

This item is a reminder to reintroduce this at the next major.

Please upvote the issue if you need to use IAM Role Chaining and we can consider working out a non-breaking way to project it.

[FilipPyrek]

This would be great! We are starting to use Pulumi for managing our AWS accounts and landing zones and this would be a handy simplification for the cross-account access.