Allow configuration of CORS headers for ACR API access from other web clients and OCI registry explorer UI clients

**What is the problem you're trying to solve**
I want to use something like JoxIt/docker-registry-ui as a custom user interface for an Azure Container Registry because the Azure Portal UI doesn't support filtered access based on tokens and scope maps but only based on Entra Security Principals.

**Describe the solution you'd like**
CORS config UI section and API for ACR allowing to set the usual "Access-Control-Allow-..." headers for this resource.
With a custom domain configured ACR should support configuring allowance for same-site requests in contrast to the default same-origin requests so that a self-hosted registry UI under the same site but a different origin is possible (i.e. common parent domain name with different subdomain).

**Additional informstion**
Currently, this can be worked around by setting up a reverse proxy server in the backend and rewrite the requests on pass-through to the ACR endpoints. But this is very cumbersome and there seem to be no good reasons why the API should not usable from external web clients directly.