[#2458] Deploy next snapshot version as computed dynamically from latest release

[lprimak]

Adds logic to Jenkinsfile to deploy a specific -SNAPSHOT version (i.e. 2.0.7-SNAPSHOT)
This version is computed by using the latest release and incrementing the patch version number.

This allows the versions that are included in the POM files to be generic (999-SNAPSHOT) without adverse consequences.

This also makes the main branch cleanly mergeable into the 3.x branch, easing 3.x updates and maintenance.

fixes #2458

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