add option to use custom secret instead of creating one with ssm #142

Job	Run time
Check	4s
Validate (cloudtrail)	11s
Validate (cloudwatch-logs)	8s
Validate (lambda-secretLayer)	11s
Validate (resource-metadata)	12s
Validate (s3)	8s
Validate (vpc-flow-logs)	8s
Build (cloudtrail)	1m 17s
Build (cloudwatch-logs)	1m 24s
Build (lambda-secretLayer)	9s
Build (resource-metadata)	55s
Build (s3)	1m 25s
Build (vpc-flow-logs)	55s
Publish	0s
	7m 7s

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