add compile_method flag and add other framework artifact types

[rbavery]

Description

Related Issue

Type of Change

• 📚 Examples, docs, tutorials or dependencies update;
• 🔧 Bug fix (non-breaking change which fixes an issue);
• 🥂 Improvement (non-breaking change which improves an existing feature);
• 🚀 New feature (non-breaking change which adds functionality);
• 💥 Breaking change (fix or feature that would cause existing functionality to change);
• 🔐 Security fix.

Checklist

• I've read the CONTRIBUTING.md guide;
• I've updated the code style using make check;
• I've written tests for all new methods and classes that I created;
• I've written the docstring in Google format for all the methods and classes that I used.

[fmigneault]

Same as previous. Any reference function to be employed?
I would assume Keras on its own has a way to generate that file, regardless of how TF can reload it. Maybe: keras.saving.serialize_keras_object (https://keras.io/api/models/model_saving_apis/serialization_utils/) ?

extra . to remove at the end

[rbavery]

I renamed all these to point to specific functions and included an argument in one of them, tf.keras.Model.export(format='tf_saved_model') that is tensorflow specific. The other two functions always output the same artifact. Would prefer to use the high level function tf.keras.Model.export(format='tf_saved_model') as the artifact type since it is what users will typically interact with rather than a lower level function like keras.saving.serialize_keras_object

[rbavery]

@fmigneault I added mlm:compile_method to the JSON Schema but this seems to have broken validation of mlm:unknown in one of the tests.

make test

――――――――――――――――――――――――――――――――――――――――――――― test_mlm_no_undefined_prefixed_field_item_properties[item_raster_bands.json] ―――――――――――――――――――――――――――――――――――――――――――――
tests/test_schema.py:61: in test_mlm_no_undefined_prefixed_field_item_properties
    with pytest.raises(pystac.errors.STACValidationError) as exc:
E   Failed: DID NOT RAISE <class 'pystac.errors.STACValidationError'>

I went through and added mlm:compile_method wherever mlm:artifact_type exists since I think we want validation behavior to be mostly the same for these fields. The only section I didn't add was

    "HasArtifactType": {
      "$comment": "Used to check the artifact type property that is required by a Model Asset annotated by 'mlm:model' role.",
      "type": "object",
      "required": [
        "mlm:artifact_type"
      ],
      "properties": {
        "mlm:artifact_type": {
          "$ref": "#/$defs/mlm:artifact_type"
        }
      }
    },

Any tips on what I need to change in the schema? I want it to be allowed under the asset role, if it is present I want it validated to be a string, but unlike mlm:artifact_type I don't want it to be required if the mlm-model role is there.