Allow for additional context to be added to Tesla calls

[unflxw]

Intercom conversation: https://app.intercom.com/a/inbox/yzor8gyw/inbox/conversation/16410700278653?view=List

The customer was following a blog post in which they pass metadata to the Telemetry Tesla middleware. They would like to use this to differentiate between different usages of Tesla. This seems particularly useful when one of those usages is sending webhooks to third parties, where the base URL itself is kind of meaningless.

We could make it so that a subset of that metadata is picked up by AppSignal and added as part of the Tesla event name (or the category?).

Alternatively, we could see if it's possible to put the name of the Tesla client module (the module that uses use Tesla) in the event name.