Allow default exporter with additional Quarkiverse exporters

[brunobat]

Description

Currently, when an exporter is present the default exporter in not instantiated.
A list of exporters through CDI is possible with Quarkiverse exporters because users can activate and deactivate each one individually, however, we need a new property to activate the default exporter, even if other ones are present.
This way we can have many different exporters and the default, working together with CDI.

[azthec]

@brunobat I can take a stab at this issue if you want

[brunobat]

Ok @azthec. Go for it!

[azthec]

@brunobat I've opened a PR, I think these are the changes you mean. I tried not to do any breaking changes but honestly I don't have to scope on the project to see what is affected.