Save contents of files into SSM Parameter Store

[joe-niland]

Is your feature request related to a problem? Please describe.
Sometimes we need to load the contents of a file into SSM Parameter Store, e.g. GCP credentials files.

Describe the solution you'd like
If the source .env/.json file contains a path, the contents of that path should be stored in SSM Parameter Store.
This feature would NOT be the default, but could be turned on with --get-file-contents

Describe alternatives you've considered
ClickOps

Additional context
n/a