feat(eventstream-serde-config-resolver): simplify and add tests

[trivikr]

Issue #, if available:
N/A

Description of changes:
simplify and add tests in eventstream-serde-config-resolver

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

[codecov-commenter]

Codecov Report

Merging #1403 into master will increase coverage by 0.47%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1403      +/-   ##
==========================================
+ Coverage   79.08%   79.56%   +0.47%     
==========================================
  Files         287      297      +10     
  Lines       11155    11328     +173     
  Branches     2360     2414      +54     
==========================================
+ Hits         8822     9013     +191     
+ Misses       2333     2315      -18     

Impacted Files	Coverage Δ
packages/util-create-request/src/index.ts	100.00% <0.00%> (ø)
packages/middleware-signing/src/middleware.ts	91.66% <0.00%> (ø)
...iddleware-sdk-s3-control/src/prepend-account-id.ts	86.95% <0.00%> (ø)
...re-bucket-endpoint/src/bucketEndpointMiddleware.ts	91.30% <0.00%> (ø)
...dk-transcribe-streaming/src/middleware-endpoint.ts	95.23% <0.00%> (ø)
...al-provider-imds/src/remoteProvider/httpRequest.ts
...dential-provider-imds/src/fromContainerMetadata.ts
...edential-provider-imds/src/remoteProvider/retry.ts
...rovider-imds/src/remoteProvider/ImdsCredentials.ts
...edential-provider-imds/src/fromInstanceMetadata.ts
... and 18 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 81b2e87...c5cff31. Read the comment docs.

[trivikr]

CodeBuild CI re-rerun was successful (details)

[AllanZhengYP]

Thank you for adding the tests!

[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.