[Metricbeat] Add index versions in the `index` metric set of the `elasticsearch` module

[bytebilly]

Following up on a Slack discussion with @consulthys.
In order to understand how many indices from previous versions are still in use, we'd like to collect more index stats to push into the overview cluster.

• settings.index.version.created
• settings.index.blocks.write

Thanks!

[consulthys]

settings.index.version.created was included into #41944 and backported to 8.x

settings.index.blocks.write will be done later