feat: Allow container linking for AWS ECS applications.

[jaffinito]

Description

• Updates our utilization payload to match new version of the spec.
• Changes the logic for where we put the docker id captured from AWS ECS
• Expands unit tests for ECS

Closes #2658

Author Checklist

• Unit tests, Integration tests, and Unbounded tests completed
• Performance testing completed with satisfactory results (if required)

Reviewer Checklist

• Perform code review
• Pull request was adequately tested (new/existing tests, performance tests)

[jaffinito]

Leaving this in draft until APM Services can take a look at the data and confirm this is working for them.

[jaffinito]

Testing has been completed and the changes are working as expected. I have set the spec change PR to ready for review and will be marking this one as ready once it gets some approvals.

[tippmar-nr]

Looks good!

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.23%. Comparing base (80cf9ef) to head (3a4002e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2683      +/-   ##
==========================================
+ Coverage   81.17%   81.23%   +0.06%     
==========================================
  Files         459      460       +1     
  Lines       29204    29229      +25     
  Branches     3223     3223              
==========================================
+ Hits        23705    23745      +40     
+ Misses       4708     4697      -11     
+ Partials      791      787       -4     

Flag	Coverage Δ
Agent	82.26% <100.00%> (+0.07%)	⬆️
Profiler	72.12% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
.../NewRelic/Agent/Core/Utilization/EcsVendorModel.cs	100.00% <100.00%> (ø)
...gent/NewRelic/Agent/Core/Utilization/VendorInfo.cs	89.13% <100.00%> (+5.30%)	⬆️

... and 1 file with indirect coverage changes