Avoid disabling google APIs on destroy

Contents (#5)

Fixes

• Avoid disabling google APIs on destroy

Add `maintainer_service_account_names` variable default

Contents (#2)

Enhancements

• Add default for maintainer_service_account_names

Other

• Adjust readme wording

Create initial module

Contents (#1)

New features

• Create first version of terraform-octue-twined-core Terraform module