Cherry-pick #20142 for V16

[kjac]

Prerequisites

• I have added steps to test this contribution in the description below

Description

This is a cherry-pick of #20142 for V16.

Due to changes in V14, we now treat UDI based local links as "legacy", and GUID based local links as "present". This caused some merge conflicts. It also required a few extra unit tests to prove that the fix for the original issue works for both types of local links. Hence this cherry-pick being a PR 😄

Testing this PR

See #20142

[AndyButland]

Looks good to me. Again, I've tested it out with variations of links and delivery API output using JSON or HTML for markup, and all seems as expected.

Naming is a little odd given we have both an anchor and a queryString field, with both containing the same value. But I assume, even if wanted to change this, we have to keep it for backward compatibility.

"tag": "a",
  "attributes": {
      "target": "",
      "anchor": "?foo=bar",
      "router-slot": "disabled",
      "title": "Ravi Motha",
      "type": "document",
      "route": {
          "path": "/people/ravi-motha/",
          "queryString": "?foo=bar",
          "startItem": {
              "id": "ca4249ed-2b23-4337-b522-63cabe5587d1",
              "path": "home"
          }
      }
  }

I'll leave you to merge just in case you want to comment or act on this point.

[kjac]

Thanks @AndyButland 👍

This does look weird, but it aligns with the V13 output:

Once you know what's happening, things becomes a little clearer.

The attributes collection in the a tag is the serialized version of the Attributes collection from the RichTextGenericElement. This collection populated straight from the markup source:

The route object in the output attributes is the serialized version of the ApiContentRoute, and this is where we find the source of the queryString output property.