Layout system implementation and applied to tool options bar (#499)

* initial layout system with tool options

* cargo fmt

* cargo fmt again

* document bar defined on the backend

* cargo fmt

* removed RC<RefCell>

* cargo fmt

* - fix increment behavior
- removed hashmap from layout message handler
- removed no op message from layoutMessage

* cargo fmt

* only send documentBar when zoom or rotation is updated

* ctrl-0 changes zoom properly

* Code review changes

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

editor/src/viewport_tools/tools/crop.rs

@@ -1,3 +1,4 @@
+use crate::layout::widgets::PropertyHolder;
 use crate::message_prelude::*;
 use crate::viewport_tools::tool::ToolActionHandlerData;
 
@@ -25,3 +26,5 @@ impl<'a> MessageHandler<ToolMessage, ToolActionHandlerData<'a>> for Crop {
 
 	advertise_actions!();
 }
+
+impl PropertyHolder for Crop {}