test: Refactor LangChain versioned tests

[amychisholm03]

Description

This PR refactors the tests in test/versioned/langchain. Before it had sub folders, openai and bedrock, to test the @langchain/openai and @langchain/aws integration respectively. The package.json contained dependencies for both of these, creating a large test version matrix.

To reduce the matrix size, langchain/openai was moved to langchain-openai and langchain/bedrock to langchain-aws. Because the vectorstore, runnables, and runnables-streaming tests for both packages test the same LangChain functionality, except for the LLM and client, I created a centralized test suite abstraction, see vectorstore.js, runnables.js, and runnables-streaming.js in the langchain folder.

How to Test

npm run versioned:major langchain
npm run versioned:major langchain-aws
npm run versioned:major langchain-openai

Related Issues

Closes #3623

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.72%. Comparing base (d1e90e4) to head (68783db).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3624      +/-   ##
==========================================
+ Coverage   89.39%   97.72%   +8.32%     
==========================================
  Files         437      438       +1     
  Lines       57537    57552      +15     
  Branches        1        1              
==========================================
+ Hits        51435    56240    +4805     
+ Misses       6102     1312    -4790     

Flag	Coverage Δ
integration-tests-cjs-20.x	73.50% <ø> (?)
integration-tests-cjs-22.x	73.54% <ø> (ø)
integration-tests-esm-20.x	52.67% <ø> (?)
unit-tests-20.x	89.08% <ø> (?)
versioned-tests-20.x	80.84% <ø> (-0.28%)	⬇️
versioned-tests-22.x	80.84% <ø> (-0.30%)	⬇️
versioned-tests-24.x	80.78% <ø> (-0.29%)	⬇️

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