feat: add field predicate types to selectionTest in vega-selections

[jonathanzong]

This change introduces the ability for vlSelectionTest to check for more types of field predicates.

This additive change will have no immediate effect, since Vega-Lite doesn't currently produce selection tuples that use these predicate types. However, future proposed changes for Animated Vega-Lite will require us to support these field predicates in addition to the existing point and interval predicates.

cc @arvind

[jonathanzong]

i believe this supersedes https://github.com/vega/vega/pull/1839 which is also very stale anyway

[jonathanzong]

bump @arvind

[domoritz]

@arvind can you wrap up the review and merge if it looks good?

[jonathanzong]

I found a potential problem here: ops in selectionResolve do a lookup with the first letter of the type name, which is assumed to be E or R. Since we are introducing new types here the lookup seem like they will fail if you try to use them.

I'm pretty confused but can look into this later but let's not merge this yet until then.

[domoritz]

I converted this pull request to a draft. Please mark it as ready.