chore(element-templates): Update element template descriptions and add keywords

[philippfromme]

Description

• adds support for a metadata property with keywords (already supported by element templates)
• in order for refactorings feature to be able to suggest better refactorings
  • updates descriptions of existing element templates
  • adds keywords to existing element templates

Related issues

Closes #3089

Checklist

• PR has a milestone or the no milestone label.

[philippfromme]

@johnBgood Can you have a look whether the update description and add keywords commits look okay? If yes, I'd continue. Also, I'm not sure why the tests are failing. I've used @ElementTemplate.Metadata in the same way as in the example.

[johnBgood]

You needed to run mvn spotless:apply, it was just a listing issue 👍
I did that, let's see if the tests are passing now.

I'll check the commits later today, or tomorrow.

[johnBgood]

@philippfromme Commits look good! :)