message: subscriber: Add a public `current_span()` method for `FmtContext`
diff: @@ -11,7 +11,7 @@ use std::{
  };
  use tracing_core::{
  field,
  - span::{Attributes, Id, Record},
  + span::{Attributes, Current, Id, Record},
  Collect, Event, Metadata,
  };
  @@ -808,6 +808,11 @@ where
  self.ctx.scope()
  }
  + /// Returns the current span for this formatter.
  + pub fn current_span(&self) -> Current {
  + self.ctx.current_span()
  + }
  +
  /// Returns the [field formatter] configured by the subscriber invoking
  /// `format_event`.
  ///
  