otelaws: adding dynamodb attributes

[jennynilsen]

When appending the middlewares to a dynamodb client, no dynamodb attributes are added to the spans.

This PR :

adds dynamodb attributes that correspond to the dynamodb operation to the spans
allows someone to provide their own function to set custom attributes
adds a way to determine the attributes to set based on service automatically

[Aneurysm9]

Thanks for this! I think I like the approach overall. My comments are mostly stylistic/structural.

[codecov]

Codecov Report

Merging #1582 (2197014) into main (f7fe163) will increase coverage by 0.7%.
The diff coverage is 98.0%.

@@           Coverage Diff           @@
##            main   #1582     +/-   ##
=======================================
+ Coverage   69.6%   70.3%   +0.7%     
=======================================
  Files        127     128      +1     
  Lines       5391    5537    +146     
=======================================
+ Hits        3755    3898    +143     
- Misses      1498    1500      +2     
- Partials     138     139      +1     

Impacted Files	Coverage Δ
...github.com/aws/aws-sdk-go-v2/otelaws/attributes.go	81.2% <62.5%> (-18.8%)	⬇️
...tation/github.com/aws/aws-sdk-go-v2/otelaws/aws.go	94.1% <100.0%> (+1.1%)	⬆️
...ion/github.com/aws/aws-sdk-go-v2/otelaws/config.go	100.0% <100.0%> (ø)
...om/aws/aws-sdk-go-v2/otelaws/dynamodbattributes.go	100.0% <100.0%> (ø)