chore(internal): support file uploads in run() helper

[dtmeadows]

• ports over support from the old run() helper to be able to upload files within run() if we're not doing base64 encoding
• adds tests for this too!

todo:

• one small thing about a custom code change I need to run by @zeke

[dtmeadows]

@zeke this is ready for a final review!

[zeke]

Looks great!

What are your thoughts on how to document replicate.run() in this client?

[dgellow]

@zeke I will merge this PR as-is for now, and will do another pass to be sure it is aligned with the typescript client.

Regarding docs, the typescript client has docs in README + some docstrings, I feel we should do the same here? And likely add an example that covers the various way to use run()