* Optionally disable trace propagation for Tesla
While we always want spans being produced, trace progation is not
desirable in all cases - namely, when calling external parties, as that
may leak sensitive information, like one present on Baggage.
This patch introduces a new option `:propagate`, that defaults to
`true`.
Some tweaks are made to existing propagation test, fixing how options
are used. The approach here is closer to what we see in some middleware
tests of Tesla itself.
* change to propagator override
* change propagator to it uses global default
* mix format
* improve docs
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Co-authored-by: Andrew Rosa <dev@andrewhr.io>
901b571b07