chore: Fix metrics lambda context and storage resolution

[hjgraca]

Please provide the issue number

Issue number: #612

Summary

WIth the new AOT release there was a problem at runtime with the serializaton of LambdaContext when capturing cold starts, the funcionname was not being set

There is also a issue with StorageResolution serialization not serializing to int instead is serializing the string "High"

Changes

• Removed the dependency of reflection for LambdaContext and bring the Amazon.Lambda.Core.ILambdaContext to Metrics.
• Add a new MetricResolutionJsonConverter to serialize StorageResolution correctly
• Remove the custom serialization StringEnumConverter for MetricsUnit and add the default JsonStringEnumConverter

User experience

Please share what the user experience looks like before and after this change

Checklist

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• Meets tenets criteria
• I have performed a self-review of this change
• Changes have been tested
• Changes are documented
• PR title follows conventional commit semantics

Is this a breaking change?

RFC issue number:

Checklist:

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

Acknowledgment

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.43%. Comparing base (33546b4) to head (7f4d676).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #613      +/-   ##
===========================================
- Coverage    72.58%   72.43%   -0.15%     
===========================================
  Files          190      190              
  Lines         7900     7897       -3     
  Branches       850      852       +2     
===========================================
- Hits          5734     5720      -14     
- Misses        1876     1889      +13     
+ Partials       290      288       -2     

Flag	Coverage Δ
unittests	72.43% <100.00%> (-0.15%)	⬇️

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[leandrodamascena]

LGTM

[hjgraca]

Not sure why is failing but codecov is green when going to the details

[amirkaws]

LGTM