rfc(tracing): Adding Distributed Tracing to Spinnaker

[mattgogerly]

Let's make troubleshooting easier.

[dbyron-sf]

This is exciting! Thank you @mattgogerly !

[mattgogerly]

It turns out Micrometer Tracing doesn't support SpringBoot < 3.0, so we'll have to use Sleuth until we get there.

I'll update the RFC accordingly.

[mattgogerly]

I've been playing around a bit and the proposed approach seems to work okay. Need to do a bit more testing to prove it out further.

Need somebody with more knowledge of Gradle to confirm if we can include the Sleuth dependencies in kork-runtime rather than adding them as implementation dependencies to every service explicitly.