Implement RED metrics recording

[adam-fowler]

Using swift-metrics
Metrics also record AWS service and operation
I've verified this works using SwiftPrometheus

[codecov]

Codecov Report

Merging #245 into master will increase coverage by 2.59%.
The diff coverage is 96.42%.

@@            Coverage Diff             @@
##           master     #245      +/-   ##
==========================================
+ Coverage   68.31%   70.91%   +2.59%     
==========================================
  Files          38       44       +6     
  Lines        4002     5140    +1138     
==========================================
+ Hits         2734     3645     +911     
- Misses       1268     1495     +227     

Impacted Files	Coverage Δ
Sources/AWSSDKSwiftCore/AWSClient.swift	91.90% <96.29%> (+2.80%)	⬆️
Sources/AWSSDKSwiftCore/ServiceConfig.swift	93.33% <100.00%> (+0.22%)	⬆️
Sources/AWSSDKSwiftCore/Doc/Region.swift	95.16% <0.00%> (-2.74%)	⬇️
Sources/AWSSDKSwiftCore/Doc/AWSShape.swift	83.05% <0.00%> (-1.74%)	⬇️
Sources/AWSSDKSwiftCore/XML.swift	83.58% <0.00%> (-0.11%)	⬇️
...ources/AWSSDKSwiftCore/Doc/AWSMemberEncoding.swift	100.00% <0.00%> (ø)
Sources/AWSSDKSwiftCore/Errors/ClientErrors.swift	53.33% <0.00%> (ø)
...ore/Encoder/CodableProperties/TimeStampCoder.swift	77.27% <0.00%> (ø)
.../Encoder/CodableProperties/CodableProperties.swift	83.87% <0.00%> (ø)
...e/Encoder/CodableProperties/CollectionCoders.swift	100.00% <0.00%> (ø)
... and 10 more

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[Yasumoto]

Definitely optional metric renames, but this looks excellent!

[adam-fowler]

Definitely optional metric renames, but this looks excellent!

Happy with the metric renames and see the logic with same prefix

[Yasumoto]

🎉