Add sdk-support entry for filter

[tristen]

Motivation

The value for filter can be an expression but there isn't an entry for sdk-support in the style spec for it. Studio uses this information for compatibility and evaluating if expression supported UIs should be present. Can we document the sdk-support information for filter expressions?

[ansis]

from talking:

Expressions are available in filters whenever they are available elsewhere. So far support for expressions in features hasn't been tracked with sdk-support. Studio should use the way it determines support for expressions in properties to determine support for expressions in filters.

I think this means we don't have to add a sdk-support key here unless we add it everywhere. Should we add sdk-support for "expression"?

[tristen]

I think this means we don't have to add a sdk-support key here unless we add it everywhere. Should we add sdk-support for "expression"?

This happened with data-driven styling version entries but the same model wasn't applied for expressions. I can always account for this in my code, it just seemed odd at first there wasn't any compatibility data for filter values.

[mollymerp]

Expressions are available in filters whenever they are available elsewhere.

Is this true? I think it isn't, at least for gl-native. Filter expression support was added by Lucas after the initial PR: mapbox/mapbox-gl-native#11251

[tristen]

I think I'm inclined to close this. There are compatibility entries for each expression and Studio should move off looking for this data from property names.