add init gcs backend script

[nerahou]

No description provided.

[antonincms]

Hello @nerahou !
Is this still needed (and for what usage) ?

[nerahou]

Hi @antonincms !
This PR was first intended to add a script to init gcs backend for terraform. I used this script to init the backend for iac-gcp-accounts. I think it would be nice to have this script on this repository.

[antonincms]

@nerahou where is it used ? I cannot find it in iac-gcp-accounts