EHN: allow for to_sql `multi` method with oracle backend
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added an entry in the latest `doc/source/whatsnew/v2.2.0.rst` file if fixing a bug or adding a new feature.

Any chance that we can add tests for this?  I'd gladly write tests, but I have no idea how. I can try mocking a SQLAlchemy db connection with an oracle back-end and then checking if the generated SQL is valid. Would that be OK? I presume the test would go somewhere in [here](https://github.com/pandas-dev/pandas/blob/main/pandas/tests/io/test_sql.py)? Thanks for the pull request, but it appears to have gone stale. If interested in continuing, please merge in the main branch, address any review comments and/or failing tests, and we can reopen. @mroeschke I tried my best to address your question and merged in the main. Could we reopen, please? Thanks @jacadzaca 