Source additional keywords provided by element templates

[nikku]

Problem you would like to solve

To solve #4802 we provided additional Camunda keywords popup menu entries so that the search picks up folks where they are. As a follow-up we want to solve the same thing for connectors, which currently solve a number of different tasks that are not properly exposed / covered by the search. As an example, as a user, I would like to add a step that creates an issue on GitHub:

Proposed solution

• Be able to provide keywords=[] in element templates
  • with schema support
  • sourced when constructing create/append/replace actions for re-usable building blocks
  • Documented as part of our element template documentation

Alternatives considered

I regard keywords as a generally usable feature. Regardless you could question whether the current "fat template" approach (one template containing all operations) is the right level of abstraction. Instead we could offer clearly defined (small) templates for individual actions.

Screenshot pending.

Additional context

I prepared the following illustration (original post) to visualize the main job our tool has: Pick up users where they are, with the job they want to execute:

[barmac]

I think the need for keywords support in the templates is independent from the discussion on fat or specialised templates. I'm moving this to ready for anybody to pick up as it's pretty straightforward what we want to accomplish.