chore(aws): Bump min SDK version

[dnys1]

Issue #, if available:

Description of changes:

• Bumps the minimum SDK version to 2.15 (from 2.12). This is to align with the rest of Amplify Dart.
• Updates mono_repo config for the AWS packages

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[codecov-commenter]

Codecov Report

Merging #1551 (2e6056f) into main (3089b1a) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1551   +/-   ##
=======================================
  Coverage   46.49%   46.49%           
=======================================
  Files         261      261           
  Lines       10190    10190           
=======================================
  Hits         4738     4738           
  Misses       5452     5452           

Flag	Coverage Δ
android-unit-tests	∅ <ø> (∅)
flutter-unit-tests	36.65% <ø> (ø)
ios-unit-tests	85.12% <ø> (ø)

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