Add support for bucket encryption feature (#8890)

- pkg/bucket/encryption provides support for handling bucket 
  encryption configuration
- changes under cmd/ provide support for AES256 algorithm only

Co-Authored-By: Poorna  <poornas@users.noreply.github.com>
Co-authored-by: Harshavardhana <harsha@minio.io>

cmd/test-utils_test.go

@@ -374,6 +374,9 @@ func UnstartedTestServer(t TestErrHandler, instanceType string) TestServer {
 	globalLifecycleSys = NewLifecycleSys()
 	globalLifecycleSys.Init(buckets, objLayer)
 
+	globalBucketSSEConfigSys = NewBucketSSEConfigSys()
+	globalBucketSSEConfigSys.Init(buckets, objLayer)
+
 	return testServer
 }
 
@@ -1977,6 +1980,9 @@ func ExecObjectLayerTest(t TestErrHandler, objTest objTestType) {
 	globalPolicySys = NewPolicySys()
 	globalPolicySys.Init(buckets, objLayer)
 
+	globalBucketSSEConfigSys = NewBucketSSEConfigSys()
+	globalBucketSSEConfigSys.Init(buckets, objLayer)
+
 	// Executing the object layer tests for single node setup.
 	objTest(objLayer, FSTestStr, t)