Generic Assay dropdown: don't show NA when name or description missing (use id instead)

[dippindots]

Fix cBioPortal/cbioportal#9041

Describe changes proposed in this pull request:

• Fix Generic Assay options show NA when name or description missing
• Add related unit tests

[dippindots]

The reason why it was showing NA:
getGenericAssayMetaPropertyOrDefault will return a default value NA when an genericAssayMetaProperty is missing and when there is no defaultValue.

export function getGenericAssayMetaPropertyOrDefault(
    meta: GenericAssayMeta,
    property: string,
    defaultValue: string = NOT_APPLICABLE_VALUE
): string {
    if (property in meta.genericEntityMetaProperties) {
        return (meta.genericEntityMetaProperties as {
            [property: string]: string;
        })[property];
    } else {
        return defaultValue;
    }
}