Tracer: add service value and coldstart false annotations

[heitorlessa]

Is your feature request related to a problem? Please describe.

When troubleshooting a larger app, service annotation would've made it easier to slice the service map in X-Ray. Similarly, ColdStart annotation is only added when there is a cold start - having false would be great to quickly analyze sampled requests where cold start happened vs warm starts.

Describe the solution you'd like

Include service annotation, Service, if value is defined, and ColdStart=false annotation.

Describe alternatives you've considered

Manually create that as part of my function

Additional context

[heitorlessa]

Note that Java and C# have already implemented the ColdStart one

[heitorlessa]

Now available as part of 1.23.0 release