Fxing S3 bucket name extraction for AWS SDK V2

[atshaw43]

Issue #, if available:
In AWS SDK V2 the S3 bucket field name was changed from BucketName to Bucket. This caused us to no longer add the field to the AWS field in the segment. Which caused it to not show up in the console.

Description of changes:
I changed it so the AWS SDK V2 instrumentation picks up the new field. This changed the field name going to the X-Ray backend, so I also added a piece of code that changes the field name back to "bucket_name" for them.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (d1c7d7b) 24.27% compared to head (4b34015) 24.59%.

Files	Patch %	Lines
...mazonaws/xray/interceptors/TracingInterceptor.java	73.33%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #393      +/-   ##
============================================
+ Coverage     24.27%   24.59%   +0.31%     
- Complexity      498      505       +7     
============================================
  Files           138      138              
  Lines          5256     5265       +9     
  Branches        635      635              
============================================
+ Hits           1276     1295      +19     
+ Misses         3797     3786      -11     
- Partials        183      184       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[wangzlei]

LGTM!