feat(tracer): add service annotation when service is set

[heitorlessa]

Issue #, if available: #850

Description of changes:

When setting service parameter or POWERTOOLS_SERVICE_NAME, Tracer will add a new annotation named Service to ease filtering a given component by service. Often times, this is used to create more meaningful X-Ray Trace Groups for larger applications.

Checklist

• Meet tenets criteria
• Update tests
• Update docs
• PR title follows conventional commit semantics

Breaking change checklist

RFC issue #:

• Migration process documented
• Implement warnings (if it can live side by side)

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

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View rendered docs/core/tracer.md

[heitorlessa]

Tested against an actual service to be triple sure, cc @cakepietoast. I'm gonna merge as I know you're busy

[codecov-commenter]

Codecov Report

Merging #861 (b0c0188) into develop (1ad18c9) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop     #861   +/-   ##
========================================
  Coverage    99.90%   99.90%           
========================================
  Files          118      118           
  Lines         5110     5125   +15     
  Branches       280      283    +3     
========================================
+ Hits          5105     5120   +15     
  Misses           2        2           
  Partials         3        3           

Impacted Files	Coverage Δ
aws_lambda_powertools/tracing/tracer.py	100.00% <100.00%> (ø)

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[michaelbrewer]

@heitorlessa - don't miss this in the changelog, a super cool improvement