feat: updates aind-data-schema

[jtyoung84]

Closes #13

• Uses Enums to construct custom_metadata and tags for Code Ocean data assets

[jtyoung84]

@dyf The main issue is that I'm not sure if the custom_metadata is correct or allowed in Code Ocean. I think that's why it was originally hard-coded since there wasn't a controlled vocabulary anywhere. Maybe we can add one in aind-codeocean-utils?

I'm not sure if this correct:

custom_metadata = {
        "modality": Modality.ECEPHYS.name,
        "platform": Platform.ECEPHYS.abbreviation,
        "data level": DataLevel.DERIVED.value,
        "subject id": mouse_subject_id,
    }
    tags = [
        Platform.ECEPHYS.abbreviation,
        mouse_subject_id,
        "curated",
        DataLevel.DERIVED.value,
    ]

[jtyoung84]

Being taken care of in #20