feat: add xray_trace_id key when tracing is active #137

[heitorlessa]

Issue #, if available: #137

Description of changes:

When X-Ray is enabled, Logger will include a xray_trace_id key with the value of the Trace ID captured from the environment.

UPDATE: Given X-Ray Trace ID will change on a per invocation we cannot support changing the order of xray_trace_id. If you don't enable X-Ray this will key only appear.

When enabled

{
    "level": "INFO",
    "location": "<module>:7",
    "message": "Testing x-ray id...",
    "timestamp": "2020-08-30 17:03:12,653",
    "service": "blah",
    "sampling_rate": 0.0,
    "xray_trace_id": "1-5759e988-bd862e3fe1be46a994272793"
}

Checklist

• Meet tenets criteria
• Update tests
• Update docs
• PR title follows conventional commit semantics
• Ensure X-Ray Trace ID is updated upon every invocation (lambda_inject_context)
• Dummy manual E2E test w/ Service Lens

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.

[codecov-commenter]

Codecov Report

Merging #150 into develop will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##           develop      #150   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           24        24           
  Lines          705       714    +9     
  Branches        68        68           
=========================================
+ Hits           705       714    +9     

Impacted Files	Coverage Δ
aws_lambda_powertools/logging/formatter.py	100.00% <100.00%> (ø)
aws_lambda_powertools/logging/logger.py	100.00% <100.00%> (ø)

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