Consistent APM Span tags for AWS SDK Requests 2

[zARODz11z]

What does this PR do?

Adds
TAG_STATE_MACHINE_ARN = 'statemachinearn'
TAG_STATE_EXECUTION_ARN = 'execution_arn'

to respective aws sdk request spans

to be in sync with JS and PY, search for the doc name above in cloud search or request link
Motivation:

SVLS-3508
Google docs Downstream Related Resources
Additional Notes:

How to test the change?

Unit tests
For Datadog employees:

• If this PR touches code that signs or publishes builds or packages, or handles
  credentials of any kind, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.

Unsure? Have a question? Request a review!

[codecov-commenter]

Codecov Report

Merging #3159 (8c63aab) into master (bdb127e) will increase coverage by 0.00%.
Report is 20 commits behind head on master.
The diff coverage is 100.00%.

❗ Current head 8c63aab differs from pull request most recent head eef709f. Consider uploading reports for the commit eef709f to get more accurate results

@@           Coverage Diff           @@
##           master    #3159   +/-   ##
=======================================
  Coverage   98.17%   98.17%           
=======================================
  Files        1284     1284           
  Lines       73911    73914    +3     
  Branches     3418     3418           
=======================================
+ Hits        72565    72568    +3     
  Misses       1346     1346           

Files	Coverage Δ
lib/datadog/tracing/contrib/aws/ext.rb	100.00% <100.00%> (ø)
lib/datadog/tracing/contrib/aws/service/states.rb	100.00% <100.00%> (ø)
...datadog/tracing/contrib/aws/service/states_spec.rb	100.00% <100.00%> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[zARODz11z]

The order of this seemed to flow better as the state_machine_arn is easier to understand

[marcotc]

These two fields are being overwritten here. Is it intentional that execution_arn overrides state_machine_arn?

[zARODz11z]

My reasoning was in a situation where execution arn and statemachine arn are present on the same request but after looking at https://docs.aws.amazon.com/sdk-for-ruby/v3/api/Aws/States/Client.html it seems that wont happen, its either or. I can replace logic with an if and else if so it wont get replaced

[marcotc]

Makes sense.
You can leave the code as is.
Can you add a comment explaining what you just mentioned above? ^ So in the future we can be confident when making changes to this method?

[zARODz11z]

comment might be unecessary now as I added .nil? to only set if it is nil

[zARODz11z]

and im not entirely confident with #3159 (comment)

[zARODz11z]

closing for now as this is a stretch goal, will revisit if it becomes a priority
(notes for edit:
Make two private helper functions 1 for extracting stuff from state_machine_arn and one for execution_arn, it will return the extracted values and then the caller will add the tags to the span.

helper1: adds state_machine_arn tag and extracts/returns other info for caller to tag
helper2: adds execution_arn tag and extracts/returns other info for caller to tag