Add OpenAI inference details

[lcawl]

Relates to #3821

This PR adds the OpenAI inference use case, with content derived from https://www.elastic.co/guide/en/elasticsearch/reference/current/infer-service-openai.html

NOTE: I made some additional changes to fix errors in the overlays, but subsequently addressed in #3930

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
inference.chat_completion_unified	⚪	Missing test	Missing test
inference.completion	⚪	Missing test	Missing test
inference.delete	⚪	Missing test	Missing test
inference.get	🟢	1/1	1/1
inference.put_openai	⚪	Missing test	Missing test
inference.put_watsonx	⚪	Missing test	Missing test
inference.put	⚪	Missing test	Missing test
inference.rerank	⚪	Missing test	Missing test
inference.sparse_embedding	⚪	Missing test	Missing test
inference.stream_completion	⚪	Missing test	Missing test
inference.text_embedding	⚪	Missing test	Missing test
inference.update	⚪	Missing test	Missing test

You can validate these APIs yourself by using the make validate target.

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
inference.chat_completion_unified	⚪	Missing test	Missing test
inference.completion	⚪	Missing test	Missing test
inference.delete	⚪	Missing test	Missing test
inference.get	🟢	1/1	1/1
inference.put_openai	⚪	Missing test	Missing test
inference.put_watsonx	⚪	Missing test	Missing test
inference.put	⚪	Missing test	Missing test
inference.rerank	⚪	Missing test	Missing test
inference.sparse_embedding	⚪	Missing test	Missing test
inference.stream_completion	⚪	Missing test	Missing test
inference.text_embedding	⚪	Missing test	Missing test
inference.update	⚪	Missing test	Missing test

You can validate these APIs yourself by using the make validate target.

[szabosteve]

Thank you so much!

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
inference.chat_completion_unified	⚪	Missing test	Missing test
inference.completion	⚪	Missing test	Missing test
inference.delete	⚪	Missing test	Missing test
inference.get	🟢	1/1	1/1
inference.put_openai	⚪	Missing test	Missing test
inference.put_watsonx	⚪	Missing test	Missing test
inference.put	⚪	Missing test	Missing test
inference.rerank	⚪	Missing test	Missing test
inference.sparse_embedding	⚪	Missing test	Missing test
inference.stream_completion	⚪	Missing test	Missing test
inference.text_embedding	⚪	Missing test	Missing test
inference.update	⚪	Missing test	Missing test

You can validate these APIs yourself by using the make validate target.

[github-actions]

The backport to 8.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-8.x 8.x
# Navigate to the new working tree
cd .worktrees/backport-8.x
# Create a new branch
git switch --create backport-3929-to-8.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 5fda5989d5c4ab21850ee1682d795c3e747c133b
# Push it to GitHub
git push --set-upstream origin backport-3929-to-8.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.x

Then, create a pull request where the base branch is 8.x and the compare/head branch is backport-3929-to-8.x.

[github-actions]

The backport to 8.18 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-8.18 8.18
# Navigate to the new working tree
cd .worktrees/backport-8.18
# Create a new branch
git switch --create backport-3929-to-8.18
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 5fda5989d5c4ab21850ee1682d795c3e747c133b
# Push it to GitHub
git push --set-upstream origin backport-3929-to-8.18
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.18

Then, create a pull request where the base branch is 8.18 and the compare/head branch is backport-3929-to-8.18.

[lcawl]

💚 All backports created successfully

Status	Branch	Result
✅	8.x

Questions ?

Please refer to the Backport tool documentation

[lcawl]

💚 All backports created successfully

Status	Branch	Result
✅	8.18

Questions ?

Please refer to the Backport tool documentation