Make Integration Linking Based On IDs, Surface Role ARN

[kolanos]

In addition to surfacing an existing cloud integration's IAM role ARN if found, this change also cleans up the lookup logic for cloud integrations in general to make it based on IDs instead of names. Link account names have been problematic as they are arbitrary and are not unique.

[codecov]

Codecov Report

Merging #150 (983d4d6) into master (8478195) will increase coverage by 10.02%.
The diff coverage is 83.33%.

@@             Coverage Diff             @@
##           master     #150       +/-   ##
===========================================
+ Coverage   54.31%   64.33%   +10.02%     
===========================================
  Files          10       10               
  Lines         580      600       +20     
===========================================
+ Hits          315      386       +71     
+ Misses        265      214       -51     

Impacted Files	Coverage Δ
newrelic_lambda_cli/utils.py	69.35% <70.00%> (+0.12%)	⬆️
newrelic_lambda_cli/api.py	58.38% <86.66%> (+40.65%)	⬆️
newrelic_lambda_cli/cli/integrations.py	90.26% <100.00%> (+0.17%)	⬆️

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