Allow a "features.attributes.disallowed_output" in tileset recipes

[HansBrende]

Hi, I'm not sure which of mapbox's many repos to file this issue under, but it would be nice if there was an option to filter out feature attributes we don't want instead of only the allowed_output option to specify those we do. (Use-case: 3rd party data sources where we don't necessarily know all of the attributes that will be present... but know for sure we can safely filter some of them out.)

If this should be filed in a different repo, feel free to close and redirect me to the correct one.