[EKS] [request]: EKS APIs do not support CORS

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**Tell us about your request**
The EKS APIs do not support CORS. This blocks browser based dashboards being created.

**Which service(s) is this request for?**
EKS

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
We are trying to build internal dashboards for users to interact with our EKS clusters, example actions include seeing how many pods are healthy in a deployment or submitting a new deployment yaml. These actions first require an EKS API DescribeCluster call to get the cluster's information like public cert and domain name. For the browser to make these calls with a language like javascript on behalf of the user (using IAM assume role) in a CORS compliant fashion sends an OPTIONS request to the API before sending the GET request. The OPTIONS request gets rejected with a message of `{"Message":"Unable to determine service/operation name to be authorized"}`.

**Are you currently working around this issue?**
Hardcoding the server and certificate authority information that would normally be pulled from the EKS API in the browser instead of dynamically getting it.

**Additional context**
N/A

**Attachments**
N/A

The issue names no repository files or tests. Start by reproducing the browser preflight OPTIONS request against the EKS DescribeCluster API and reviewing the EKS API/CORS behavior. Done means browser-based callers can make the described API requests without the current authorization error.

Written by the indexing model from the issue text.