Add block id asciidoc reference for code example in alternative_report.json

[ezimuel]

I'm building a report to track the code examples for each client repositories (see https://github.com/elastic/clients-team/pull/114). I would like to have the link to the Elastic documentation where the code example is available. Now, we have the anchor link with the digest (thanks to #1717) but I don't have the HTML page name.
I'm using the alternatives_report.json as source and we have only the asciidoc file for each code example. We need also the asciidoc block id to find out the HTML page name.

For instance, this code example getting-started-index.html#3f3b3e207f79303ce6f86e03e928e062
is located in getting-started.asciidoc but the URL of the HTML page is getting-started-index.html. In order to get this URL I need the [[getting-started-index]] block id in the alternative_report.json for the code example. Can we add this block name in the source_location?

For instance, something like this:

{
    "source_location": {
        "file": "getting-started.asciidoc",
        "block": "getting-started-index",
        "line": 253,
    },
    "digest":"3f3b3e207f79303ce6f86e03e928e062",
}

Thoughts?

CC @elastic/es-clients-core

[nik9000]

This should be possible, with our migration away from docbook. But it is a bit more difficult than you'd expect.

[gtback]

Yeah, we don't enforce a correspondence between the input asciidoc file and the output HTML chunk. I'll have to look into how easy it would be for the chunker to add this information to the alternatives report.