Add option to adjust viewport zoom rate in the preferences dialog (#2420)

* zoom rate preference

* Add generic range mapping functions for improved reusability

* cleanup

* Map zoom slider's default value of 50 to the original zoom rate (0.005)

* use . instead of .0 for whole-number floats

* Refactor zoom rate mapping to use a fixed reference point and adjustable curve steepness

* Code review

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>

editor/src/messages/preferences/preferences_message_handler.rs

@@ -1,3 +1,4 @@
+use crate::consts::VIEWPORT_ZOOM_WHEEL_RATE;
 use crate::messages::input_mapper::key_mapping::MappingVariant;
 use crate::messages::portfolio::document::node_graph::utility_types::GraphWireStyle;
 use crate::messages::preferences::SelectionMode;
@@ -13,6 +14,7 @@ pub struct PreferencesMessageHandler {
 	pub use_vello: bool,
 	pub vector_meshes: bool,
 	pub graph_wire_style: GraphWireStyle,
+	pub viewport_zoom_wheel_rate: f64,
 }
 
 impl PreferencesMessageHandler {
@@ -47,6 +49,7 @@ impl Default for PreferencesMessageHandler {
 			use_vello,
 			vector_meshes: false,
 			graph_wire_style: GraphWireStyle::default(),
+			viewport_zoom_wheel_rate: VIEWPORT_ZOOM_WHEEL_RATE,
 		}
 	}
 }
@@ -99,6 +102,9 @@ impl MessageHandler<PreferencesMessage, ()> for PreferencesMessageHandler {
 				self.graph_wire_style = style;
 				responses.add(NodeGraphMessage::SendGraph);
 			}
+			PreferencesMessage::ViewportZoomWheelRate { rate } => {
+				self.viewport_zoom_wheel_rate = rate;
+			}
 		}
 		// TODO: Reenable when Imaginate is restored (and move back up one line since the auto-formatter doesn't like it in that block)
 		// PreferencesMessage::ImaginateRefreshFrequency { seconds } => {