feat(middleware-stack): allow adding middleware to override an existing one

[AllanZhengYP]

Fixes: #1935

Resolve a bug introduced in #1883, more details covered in #1935

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov-io]

Codecov Report

Merging #1964 (bc46a83) into master (f2a47e8) will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1964      +/-   ##
==========================================
+ Coverage   79.30%   79.34%   +0.03%     
==========================================
  Files         368      368              
  Lines       15132    15170      +38     
  Branches     3222     3241      +19     
==========================================
+ Hits        12001    12037      +36     
- Misses       3131     3133       +2     

Impacted Files	Coverage Δ
packages/util-waiter/src/utils/validate.ts	81.81% <0.00%> (-18.19%)	⬇️
lib/storage/src/data-chunk/readable-helper.ts	86.84% <0.00%> (-5.47%)	⬇️
packages/util-dynamodb/src/convertToAttr.ts	98.70% <0.00%> (-1.30%)	⬇️
packages/util-waiter/src/poller.ts	100.00% <0.00%> (ø)
packages/util-waiter/src/waiter.ts	100.00% <0.00%> (ø)
protocol_tests/aws-ec2/endpoints.ts	81.48% <0.00%> (ø)
protocol_tests/aws-json/endpoints.ts	81.48% <0.00%> (ø)
packages/middleware-ssec/src/index.ts	82.60% <0.00%> (ø)
protocol_tests/aws-query/endpoints.ts	81.48% <0.00%> (ø)
packages/util-dynamodb/src/marshall.ts	100.00% <0.00%> (ø)
... and 49 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 63ad215...afcabc5. Read the comment docs.

[aws-sdk-js-automation]

AWS CodeBuild CI Report

• CodeBuild project: sdk-staging-test
• Commit ID: afcabc5
• Result: SUCCEEDED
• Build Logs (available for 30 days)

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

[github-actions]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs and link to relevant comments in this thread.