Carry the learned denoise's switch and grain as edit settings

Whether to use the learned denoise, and how much grain to keep, are what a
photographer sets, so they travel the one road every setting does: published
as a capability, captured by Preset, stored in the sidecar, replayed by the
undo stack (FR-DEV-3c). Published only on a photograph that can take it, for
the lens switch's reason; the availability is derived from the file and is
not in the state. Off by default, grain 0; a reset returns both.

core/dr-pipeline/src/lib.rs

@@ -40,6 +40,7 @@ pub mod detail;
 pub mod framing;
 pub mod graph;
 pub mod history;
+pub mod learned_denoise;
 pub mod lens;
 pub mod mask;
 pub mod neutral;