Add feedback for forecasting

[americast]

Provide feedback when Forecasting UDF is called in the following ways:

• Reporting confidence intervals
• Returning a metric for the forecasting performance.
• Providing suggestions in simple special cases, such as during Flat predictions.

Eg:

SELECT HomeForecast();

SUGGESTION: Predictions are flat. Consider using LIBRARY 'neuralforecast' for more accrate predictions.

Partially fixes #1257 and #1243.

[americast]

Another concern with this approach is that the suggestion is being provided through a print statement. Hence, it would appear on the server side, and the user might miss it. Any hints on how we can send the suggestion to the user?

[xzdandy]

Another concern with this approach is that the suggestion is being provided through a print statement. Hence, it would appear on the server side, and the user might miss it. Any hints on how we can send the suggestion to the user?

Good point. I think one option is to make the suggestion as part of the CREATE FUNCTION 's output.

[xzdandy]

Hi @americast, thanks for adding for suggestions a metric for the forecasting performance. Do you think we can add that information into evadb/catalog/models/function_catalog.py or evadb/catalog/models/function_metadata_catalog.py? We can decide which catalog table is better. The idea is to be able to query this information afterwards.

Beside, we can also output this information as part of the output of CREATE FUNCTION, so user can directly view them.

[americast]

@xzdandy The issue seems to be coming up due to multithreading while training neuralforecast model on the GPU -- the entire test suite seems to be getting spawned into multiple threads and thus it appears to have got hanged. For now I have removed test for neuralforecast.