feat: cloud_upload(<filename>) table func

[greyscaled]

Summary

When a file is uploaded via GlareDB Cloud, it can be read with cloud_upload(<filename>).

This function can only be called in remote and hybrid contexts; it is not meaningful locally.

The filename must contain a valid extension (foo.csv).

Example

After uploading a file called test.csv to GlareDB Cloud, it can be accessed like:

SELECT * FROM cloud_upload('test.csv');

and joined with other data sources, etc.

Details

MVP File Format Limitations

Presently only:

• CSV as filename.csv
• Parquet as `filename.parquet
• Newline-delimited JSOn as filename.json

are accepted.

The file name must currently include the extension.

The file can only use alphanumeric characters.

Testing

I tested this by building the image and running with a GlareDB Cloud environment.
I think it's tractable to write an integration test for this function, in the same vein
as other integration tests, but I'd prefer to leave this as a follow-up refinement
item.

Resolves: #2614

[tychoish]

this all seems good, and I'd be fine merging it.

• we could probably write tests for this using mino or the mock gcs fixture, but it'd be gnarly. Shouldn't do that today.
• before we merge we should definitely go around and make sure the name is good.
• want to make sure that it errors correctly, when running in pure local or embedded.

[greyscaled]

want to make sure that it errors correctly, when running in pure local

It does and we can easily add that test, I see no harm in it.

[tychoish]

It does and we can easily add that test, I see no harm in it.

I was moving too quick mostly meant: "a really good error message" and not, say ("credentials not found") or something else.