Add service account additional labels

[pat-kearney]

What this PR does / why we need it:

Adding options for additional labels on the RBAC service accounts. Implemented much like the additional annotations.
Example usage: adding workload identity labels within AKS.

Which issue this PR fixes

(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged)

• fixes #

Special notes for your reviewer:

More baseline files were updated than I expected. This appears to be because they are not currently up to date in a couple of places and then others due to the version bump.

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• [ x] Chart Version bumped
• [ x] Documentation has been updated with helm-docs (run: .github/helm-docs.sh)
• [ x] CHANGELOG.md has been updated
• [ x] Variables are documented in the README.md
• [ x] For Datadog Operator chart or value changes update the test baselines (run: make update-test-baselines)

[fanny-jiang]

Thanks for your contribution! I made some updates, but otherwise LGTM.