auth: Allow adding HTTP Headers in LUA Record ifurlup

[pieterlexis]

Short description

This PR adds support for a headers option in the ifurlup. In order to achieve this, I added an std::variant-based method of setting options to allow arrays as values in the options, that could be useful in the future.

I can recommend reviewing on a per-commit basis.

Closes: #8295
Closes: #11610

Checklist

I have:

• read the CONTRIBUTING.md document
• read and accepted the Developer Certificate of Origin document, including the AI Policy, and added a "Signed-off-by" to my commits
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)

[miodvallat]

Why not.

[miodvallat]

Why not.