Add region parameter back to TF setup.Configuration

[erhancagirici]

Description of your changes

Fixes #1220

1204 removed obsolete TF-CLI related configuration codepath and switched to native TF SDK configuration.

As a result of native SDK configuration, terraform.Setup.Configuration was no longer needed to configure TF AWS client and we cease

However, several external name configurations which use external name templates, still rely on terraform.Setup.Configuration map to obtain region value.

The change adds the region parameter back to terraform.Setup.Configuration.

I have:

• [x] Read and followed Crossplane's [contribution process].
• [x] Run make reviewable to ensure this PR is ready for review.
• [x] Added backport release-x.y labels to auto-backport this PR if necessary.

How has this code been tested

With uptest, create resources that uses .setup.configuration in their external name configs

[erhancagirici]

/test-examples="examples/sns/v1beta1/topic.yaml"

[mbbush]

/test-examples="examples/kinesis/v1beta1/stream.yaml"

[github-actions[bot]]

Successfully created backport PR #1222 for release-1.2.