Use new release links in release progress view

What does this MR do?

Updates the release progress view frontend to begin using the links added to the GraphQL endpoint in !46161 (merged).

Also, all references to open* links have been renamed to opened* to align with the updated field names coming from GraphQL (see !46497 (merged)).

Screenshots

Before	After

Feature flag

The new links are hidden behind a release_mr_issue_urls feature flag which is currently disabled by default. Because of this, no changelog is needed. The changelog will be included with the MR that enables these links by default.

When the links aren't provided by the backend, the frontend falls back to rendering these links as plain text (as can be seen in the Before image above).

Related to #205295 (closed)