Fix Keras materializer to work with remote artifact stores

[safoinme]

Describe changes

Change the Keras model materializer to support the Azure artifact store. By saving the model in a temp file then use fileio to copy it to remote storage.

        with tempfile.NamedTemporaryFile(
            mode="w", suffix=".hdf5", delete=True
        ) as f:
            model.save(f.name)
            fileio.copy(f.name, filepath)

Pre-requisites

Please ensure you have done the following:

• I have read the CONTRIBUTING.md document.
• If my change requires a change to docs, I have updated the documentation accordingly.
• If I have added an integration, I have updated the integrations table.
• I have added tests to cover my changes.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Other (add details above)

[htahir1]

This is a cool change 🚀. I'm unsure whether the PR title is accurate though. It not only works with Azure store but also all remote stores now right?

[htahir1]

Do we need this here?

[safoinme]

Yes, it's for every remote storage.
Sorry I will remove it, we don't need it actually

[htahir1]

LGTM!

[bcdurak]

Amazing changes. Everything looks great