fix(openai): allow tokens or token arrays as input for Embeddings endpoint

[Yun-Kim]

Fixes #5884.

This PR adds handling for non-string request input params for the Embeddings.create() method. This API method accepts strings, array of strings, as well as token arrays (list of ints) and arrays of token arrays (list of list of ints), but the previous implementation only accounted for strings and array of strings. Token arrays or arrays of token arrays being passed in as arguments would then cause errors as the traced request handler for the Embeddings endpoint did not account for non-string types.

Checklist

• Change(s) are motivated and described in the PR description.
• Testing strategy is described if automated tests are not included in the PR.
• Risk is outlined (performance impact, potential for breakage, maintainability, etc).
• Change is maintainable (easy to change, telemetry, documentation).
• Library release note guidelines are followed.
• Documentation is included (in-code, generated user docs, public corp docs).
• OPTIONAL: PR description includes explicit acknowledgement of the performance implications of the change as reported in the benchmarks PR comment.

Reviewer Checklist

• Title is accurate.
• No unnecessary changes are introduced.
• Description motivates each change.
• Avoids breaking API changes unless absolutely necessary.
• Testing strategy adequately addresses listed risk(s).
• Change is maintainable (easy to change, telemetry, documentation).
• Release note makes sense to a user of the library.
• Reviewer has explicitly acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment.

[pr-commenter]

Benchmarks

Comparing candidate commit a598843 in PR branch yunkim/fix-openai-embeddings-arg with baseline commit f5854aa in branch 1.x.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 94 cases.