Migrate from IRSA to Pod Identities

[JoeNorth]

Is your feature request related to a problem? Please describe.
Pod Identities provide a simpler way to assign permissions to pods running in EKS. The workshop should advocate for its use over IRSA.

Describe the solution you'd like

1. Review all workshop content for the use of IRSA
2. Review the components for support for Pod Identities
3. Where support is available, update the workshop to use Pod Identities instead of IRSA

Cluster creation steps and corresponding eksctl template in aws-samples/python-fastapi-demo-docker will need to be updated to install the pod identity addon and remove IRSA components.

Describe alternatives you've considered
N/A

Additional context
N/A