Error codes for improved troubleshooting

[doodlesbykumbi]

Is your feature request related to a problem? Please describe.

Well-defined error codes simplify the troubleshooting experience. Authn-k8s client and Secrets provider have both shown the benefits. These also make it possible to have app analytics that monitor the statistics of such errors.

Describe the solution you would like

Error have unique error codes

Describe alternatives you have considered

N/A

Additional context

N/A