[schema] More permissive patterns for signal topics and hardware parameters

[eeberhard]

As raised by @domire8 in #386, we should extend the pattern properties for signal topics and hardware parameters in the application schema to allow more than just lower_snake_case

[domire8]

We forgot to do that before 2-1-0.

In common/signal.schema.json, the name of a topic should also be more permissive IMO, it could be the case that one wants to use an outside topic name that has capital letters

However, reading this now, I'm lacking a bit the reasoning behind. Topic names can already be anything, it's just a string without validation. I don't think this is still relevant.

Making hardware parameters more permissive is still a valid point, I could just make a PR to do that, and it will get released with the next schema update?