Refactor lib/plugins/aws/utils with Async

[mdanyalkhan]

Addresses: #{8368}
Configures all promise-related functions as async functions.

[codecov]

Codecov Report

Merging #10309 (ca49ff5) into master (9faf37a) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master   #10309   +/-   ##
=======================================
  Coverage   85.42%   85.42%           
=======================================
  Files         339      339           
  Lines       13919    13919           
=======================================
  Hits        11891    11891           
  Misses       2028     2028           

Impacted Files	Coverage Δ
lib/plugins/aws/utils/resolveCfImportValue.js	62.50% <ø> (ø)
lib/plugins/aws/utils/resolveCfRefValue.js	66.66% <ø> (ø)
lib/plugins/aws/utils/credentials.js	90.62% <100.00%> (ø)

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[medikoo]

Thank you @mdanyalkhan !