Build and Test Oracle R2DBC with a Github Action

[Michael-A-McMahon]

(Please don't merge yet: I'm using this pull request just to trigger the action and verify if it works)
I'm planning to add another action that executes our tests as well.

[Michael-A-McMahon]

In the last test run, looks like the action hung on OracleBatchImplTest. Most likely that's due to Issue #5, where concurrent SQL execution and row processing leads to a blocked thread. I'd figure the Github runner is a single core virtual environment, which means ForkJoinPool.commonPool() has just one thread. When you've got a pool of just one thread, and that thread is blocked, you're not going to make progress any time soon.
Once #15 is approved and merged into main, we can give this test action another shot.

[Michael-A-McMahon]

This pull request is now (finally) ready for review and, if approved, it may be merged into the main branch. With this action in our repo, an automated test run will begin whenever there is a pull request.

After pulling in the latest changes from main, the tests are no longer failing or getting stuck.