server(tracing): add spans in compiler and webhook

[plyr4]

Description

now that go-vela/server#899 is in, we should expand on it and add a few spans to track what takes so long to compile large pipelines and process webhooks. it might also give us more insight into parts of the code that might not be running as fast as we expect.

Value

accuracy in how we can optimize our biggest bottlenecks.