Closes https://gitlab.com/components/opentofu/-/issues/23

The ref name may include slashes indicating directories
in a filename and as such we would have to pre-created those
which we do not want. The filename does not matter,
thus, the SHA is as good.

This change set locks down the access to the plan artifacts to `none` by
default. This can be changed by setting the `artifcats_access` or
`plan_artifacts_access` input.

Changelog: changed

Closes https://gitlab.com/components/opentofu/-/issues/29

git grep -l '\s\+$' | xargs sed -e 's/\s\+$//' -i

Even though it is against the CI/CD component best practices this always
for a smoother transition from the Terraform CI/CD templates.
We can remove that proxy again in a later major version.

Closes #8