* pre PR commit
* added IAM functionality
* clean up of readme
* versions.tf fix
* added separate iam.tf, facilitated existing secret manager module
* corrected optional variable defaults
* adjusted readme to new changes
* adjusted tftest line in readme for changed example
* reverted the module back to a state where it only manages one instance
* minor fix for main readme.md
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Co-authored-by: Julio Castillo <jccb@google.com>
