Rename ZMQ plugin

[mavam]

:notebook_with_decorative_cover: Description

The PR renames the ZeroMQ plugin from zmq-app to zmq. For one, the dash caused bugs in combination with Dynaconf and configuration (zmq-app vs zmq_app). Moreover, the suffix -app is a bit confusing because it's technically a plugin.

:memo: Checklist

• [x] All user-facing changes have changelog entries.
• [x] The changes are reflected on docs.tenzir.com/threatbus, if necessary.
• [x] The PR description contains instructions for the reviewer, if necessary.

:dart: Review Instructions

TBD

[lava]

Maybe we can use this PR for renaming pyvast-threatbus -> vast-threatbus as well, if we're doing breaking changes anyways.

[dominiklohmann]

Maybe we can use this PR for renaming pyvast-threatbus -> vast-threatbus as well, if we're doing breaking changes anyways.

I'll do that in a separate PR so we have an easier time adapting downstream.