Restore 4.1.0 snapshots once cleanup has completed on 4.0.x

[snicoll]

main currently has a number of changes that are not tracked properly with the current 4.1.0 milestone being empty. While we work on these changes, we'd like to backup the current main to review-4.1.x and force push main to the state of 4.0.x.

Once the migration completes, we'll branch 4.0.x again and then review and apply the changes in review-4.1.x accordingly.

This impacts the following issues:

• Add support for WSS4J subject cert constraints #1419
• Upgrade to Apache WSS4J 4.0.0 #1429
• Update HttpComponents5ClientFactory to use setConnectionTimeout #1437
• 0bd5441 (can be applied to 4.0.x)
• d4b489a (can be applied to 4.0.x)
• Add Observation implementation #1438
• 3214e8c (can be applied to 4.0.x)

[snicoll]

The XStream upgrade is no longer necessary as it isn't used anymore by the Gradle build. The two other commits that could have been added in 4.0.x are no longer relevant either.

[snicoll]

We're almost there, I am not sure we'll have the time to review #1438 before M1.