Improve how to get different types of `DispatchInfo.target`

[llucax]

What's needed?

It is difficult to use the current targets, defined as TargetComponents = list[int] | list[ComponentCategory], because the match statement (and isinstance() can't deal with containers, so we can check that something is a list but not that is a list[int]. We had issues in the past getting this right and we still do.

Proposed solution

Wait until this is implemented in the client:

• Improve how to get different types of Dispatch.target frequenz-client-dispatch-python#139

And then use the same solution here.

Use cases

No response

Alternatives and workarounds

No response

Additional context

This is mostly a reminder that we should update this library and the DispatchInfo class after frequenz-floss/frequenz-client-dispatch-python#139 is merged and released.