Log the extra-meta data we burn into the package for better testability

[dbast]

Description

This an improvement to #4303, which enabled to burn-in extra meta data into packages. The feature is used to e.g. burn-in CI_RUN_IDs, GIT_URL, GIT_SHA1 into packages to be able to trace them back to specific build runs and commits in the recipe feedstock.

Its currently pretty cumbersome to check if a build run embeds the right extra meta data or not (requires inspecting the resulting package).

This PR:

• makes it much easier by logging the extra-meta data that is burn-in into the build log.
• makes it much easier to co-relate a package and its build log as both contain the same extra meta data

This particularly helps to test conda-forge/conda-smithy#1577 and also constantly check via future build logs that the right meta data is in place.

pinging also @jaimergp :)

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[jaimergp]

LGTM! The Windows failure looks like a race condition unrelated to this.