chart: Add annotations for service account

[sayboras]

In order to use AWS EKS IAM Roles for Service Accounts feature, one must annotate the service account to specify what IAM role admin wants to grant to that service account.

apiVersion: v1
kind: ServiceAccount
metadata:
  annotations:
    eks.amazonaws.com/role-arn: arn:aws:iam::AWS_ACCOUNT_ID:role/IAM_ROLE_NAME

[codecov-io]

Codecov Report

Merging #521 into master will not change coverage by %.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #521   +/-   ##
=======================================
  Coverage   50.29%   50.29%           
=======================================
  Files          63       63           
  Lines        4939     4939           
=======================================
  Hits         2484     2484           
  Misses       2044     2044           
  Partials      411      411           

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[stefanprodan]

LGTM