Include group name in Command.java assertions

[nhomble]

The application failed to start up because of Assertions in Command. Specifically, I was hit by Help constructor which asserts that description has text. I think the assertion is great, but I had to put debug points to finally figure out which class had the offender. Since group is usually defined (since we default to the class name when a name isn't explicitly defined) in StandardMethodTargetRegistrar::getOrInferGroup I think we could just add this to the assertion message for clarity?

[jvalkeal]

We're doing housekeeping in issues and closing ones which are potentially stale due to recent changes in a project. We are now more up to date with Spring Boot starting with release 2.1.0 and work in 3.x making shell compatible with Spring Framework 6 and Spring Boot 3.

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