Christopher Durham 09da422a76
subscriber: add Filter::event_enabled (#2245)
## Motivation

Like for `Subscriber` and `Layer`, allow per-layer `Filter`s to filter
based on event fields.

## Solution

Add `Filter::event_enabled`, plumb it through the combinator
implementations, and call it from `Filtered`.

The bit I'm the least confident about is the check in `Registry`'s
implementation, but I *think* it matches what `event` is doing and
everything seems to function correctly.
2022-07-29 11:27:33 -07:00
..