fix: attribute names for google_cloud_ids_endpoint

[modular-magician]

The API uses camel case instead of snake case which is used by terraform.

Without this patch the attributes endpoint_forwarding_rule and endpoint of google_cloud_ids_endpoint are an empty string rendering the resource unusable.

If this PR is for Terraform, I acknowledge that I have:

• Searched through the issue tracker for an open issue that this either resolves or contributes to, commented on it to claim it, and written "fixes {url}" or "part of {url}" in this PR description. If there were no relevant open issues, I opened one and commented that I would like to work on it (not necessary for very small changes).
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• Ensured that all new fields I added that can be set by a user appear in at least one example (for generated resources) or third_party test (for handwritten resources or update tests).
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Release Note Template for Downstream PRs (will be copied)

cloudids: fix `endpoint_forwarding_rule` and `endpoint_ip` attributes for `google_cloud_ids_endpoint`

Derived from GoogleCloudPlatform/magic-modules#6712

[github-actions]

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