Title: Integrating Rust binaries in tracer extensions

Description:
Hi envoy team, as you might know Datadog is currently integrating a tracer into envoy. As a result of a company initiative to harmonize implementations that are common to the different tracers implemented inside the company we'd have the need to use this common modules into the dd-trace-cpp project. The language of choice for those common modules is Rust which means we'd need to either compile Rust code inside envoy project or importing a precompiled binary during the compilation of the extension. I've tried to look for another extensions using any of the aforementioned mechanisms to integrate Rust code but, unfortunately, I had no luck. So Is there a way to integrate Rust code/libraries in a tracer?
Aside from that I've found this PR, with that we could build a dynamic library which will include the cpp tracer and the rust parts to be loaded upon envoy initialization right?

Relevant Links:
https://github.com/envoyproxy/envoy/tree/main/source/extensions/tracers/datadog
#2252