Remove hardcoded links to link references, use advertised path from the registry

[Mpdreamz]

After #732 landed we now publish links.json files for cloud but on master.

https://elastic-docs-link-index.s3.us-east-2.amazonaws.com/elastic/cloud/master/links.json

This PR removes hardcoded paths to /main/links.json and uses paths as advertised by the links registry.

https://elastic-docs-link-index.s3.us-east-2.amazonaws.com/link-index.json

"cloud": {
      "master": {
        "repository": "cloud",
        "path": "elastic/cloud/master/links.json",
        "branch": "master",
        "etag": "64f49248eb9d421065125c346b4d0ce4"
      }
    },

[Copilot]

Pull Request Overview

This pull request removes hardcoded link references and instead relies on advertised paths obtained from a links registry. Key changes include:

• Updating method signatures in CrossLinkResolver to accept FetchedCrossLinks for consistent link lookup.
• Changing the GetBranch method in IUriEnvironmentResolver from private to public and adding a new branch mapping for the "cloud" scheme.
• Refactoring and extending fetcher and configuration classes to support the new LinkIndexEntries property and to cover the newly added "cloud" repository.

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/Elastic.Markdown/CrossLinks/CrossLinkResolver.cs	Updated TryFullyValidate and LookupLink to include fetchedCrossLinks for link resolution.
src/Elastic.Markdown/CrossLinks/IUriEnvironmentResolver.cs	Exposed GetBranch as public and added a new mapping for "cloud" to "master".
docs/testing/cross-links.md	Added a new example for a "cloud" link reference.
tests/Elastic.Markdown.Tests/TestCrossLinkResolver.cs	Updated tests to incorporate new LinkIndexEntries in the fetched cross links.
src/Elastic.Markdown/CrossLinks/CrossLinkFetcher.cs	Modified link index fetching logic to prioritize both "main" and "master" branch scenarios.
src/Elastic.Markdown/InboundLinks/LinkIndexLinkChecker.cs	Adjusted link index URL construction to use LinkIndexEntries when available.
docs/_docset.yml	Added the "cloud" repository to the cross_links configuration.
src/Elastic.Markdown/InboundLinks/LinkIndexCrossLinkFetcher.cs, ConfigurationCrossLinkFetcher.cs, AssemblerCrossLinkFetcher.cs	Refactored variable names and added retrieval of LinkIndexEntries for consistency.

Comments suppressed due to low confidence (3)

src/Elastic.Markdown/CrossLinks/CrossLinkResolver.cs:114

• [nitpick] Consider extracting the lookupPath computation into a dedicated helper method to reduce duplication and improve clarity.

var lookupPath = (crossLinkUri.Host + '/' + crossLinkUri.AbsolutePath.TrimStart('/')).Trim('/');

src/Elastic.Markdown/CrossLinks/IUriEnvironmentResolver.cs:24

• [nitpick] Since GetBranch is now public and includes a new case for 'cloud', update its documentation/comments to clearly describe its behavior and branch mapping.

public static string GetBranch(Uri crossLinkUri)

tests/Elastic.Markdown.Tests/TestCrossLinkResolver.cs:49

• Add test cases to verify the link resolution logic for the new 'cloud' repository scheme and to ensure both 'main' and 'master' branch scenarios are correctly handled.

DeclaredRepositories.AddRange(["docs-content", "kibana", "elasticsearch"]);