Add ServiceAccount to the default watching list (#211)

**What this PR does / why we need it**:

**Which issue(s) this PR fixes**:

Fixes #

**Does this PR introduce a user-facing change?**:
<!--
If no, just write "NONE" in the release-note block below.
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```release-note
NONE
```

This PR was merged by Kapetanios.

pkg/app/piped/livestatestore/kubernetes/reflector.go

@@ -68,6 +68,7 @@ var (
 		"PersistentVolume":         {},
 		"PersistentVolumeClaim":    {},
 		"HorizontalPodAutoscaler":  {},
+		"ServiceAccount":           {},
 		"Role":                     {},
 		"RoleBinding":              {},
 		"ClusterRole":              {},