chore(cli): separate parsing config files from using the config data

[otaviomacedo]

Right now we read the configuration files directly to get the region. In the future, we may need to get other configuration from these files.

This change separates two concerns: reading and merging the files on one hand, and using the configuration data, on the other.

If we had this clear separation of concerns before we migrated to SDK v3, it would have reduced the risk for one of the regressions.

Copied from the SDK code itself.

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[aws-cdk-automation]

➡️ PR build request submitted to test-main-pipeline ⬅️

A maintainer must now check the pipeline and add the pr-linter/cli-integ-tested label once the pipeline succeeds.

[aws-cdk-automation]

The pull request linter has failed. See the aws-cdk-automation comment below for failure reasons. If you believe this pull request should receive an exemption, please comment and provide a justification.

A comment requesting an exemption should contain the text Exemption Request. Additionally, if clarification is needed add Clarification Request to a comment.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.51%. Comparing base (bf77e51) to head (fdfd639).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #32371      +/-   ##
==========================================
+ Coverage   78.50%   78.51%   +0.01%     
==========================================
  Files         106      106              
  Lines        7201     7210       +9     
  Branches     1321     1322       +1     
==========================================
+ Hits         5653     5661       +8     
- Misses       1361     1362       +1     
  Partials      187      187              

Flag	Coverage Δ
suite.unit	78.51% <100.00%> (+0.01%)	⬆️

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

Components	Coverage Δ
packages/aws-cdk	78.51% <100.00%> (+0.01%)	⬆️

[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: fdfd639
• Result: SUCCEEDED
• Build Logs (available for 30 days)

Powered by github-codebuild-logs, available on the AWS Serverless Application Repository

[aws-cdk-automation]

The pull request linter fails with the following errors:

❌ CLI code has changed. A maintainer must run the code through the testing pipeline (git fetch origin pull/32371/head && git push -f origin FETCH_HEAD:test-main-pipeline), then add the 'pr-linter/cli-integ-tested' label when the pipeline succeeds.

PRs must pass status checks before we can provide a meaningful review.

If you would like to request an exemption from the status checks or clarification on feedback, please leave a comment on this PR containing Exemption Request and/or Clarification Request.

[github-actions]

Comments on closed issues and PRs are hard for our team to see.
If you need help, please open a new issue that references this one.