Ability to add annotations to service account

[mikeywuu]

TL;DR

The created service account from the chart currently allows no customization in any form. I have the requirement to share the same name as the templated service account while also adding some vault related annotations to it.

Expected behavior

Add the ability to pass annotations via the helm values to the service account. I could offer to create the necessary changes in a PR, if desired.

[lukasmetzner]

Hey, sounds good to me. Feel free to open up a PR for this issue.