Improve Maven setup

[artur-ciocanu]

Currently we have quite a few modules in the Java SDK. However the Maven setup is far from ideal.

Here are a few if the issues that have been identified:

• Version management - we have different dependencies spread across modules. Sometimes versions are conflicting
• Incorrect plugin management
• Duplicated dependencies - this is problematic for upgrades and also when dealing with things like tests and examples since some of those are quite different.

The plan is to have a few PRs that would address this one by one.