Lenny Podcast example import

[jexp]

• disable warnigs for the driver
• and document that the OPENAI_API_KEY is required
• probably fail fast when it is not set

But after setting these, it looks really good with the import

[johnymontana]

Podcast transcript files now available here: https://s3.us-west-1.amazonaws.com/data.neo4j.com/lennys_podcast_transcripts_archive.zip

Update the Lenny's podcast example app readme instructions, build scripts, and makefile targets to download and extract the transcript txt files from this url. add tests, including an integration test that verifies the file is available