Welcome screen, refactor to allow zero documents, and add TS typing to widgets (#702)

* unfinished implementation

* Add frontend for the empty panel screen

* Add an icon for Folder based on NodeFolder

* fixed messages causing peicees of ui not to render on new document

* Standardize nextTick syntax

* WIP generisization of component subscriptions (not compiling yet)

* Fix crash when loading font and there is no active document

* Only advertise tool actions with a document

* Fix failure to create new document

* Initalise the properties panel

* Fix highlight tab, canvas jump, warns and layer tree

* Fix tests

* Possibly fix some things?

* Move WorkingColors layout definition to backend

* Standardize action macro formatting

* Provide typing for widgets in TS/Vue and associated cleanup

* Fix viewport positioning initialization

* Fix menu bar init at startup not document creation

* Fix no viewport bounds bug

* Change !=0 to >0

* Simplify the init system

Closes #656

Co-authored-by: Keavon Chambers <keavon@keavon.com>
Co-authored-by: 0hypercube <0hypercube@gmail.com>

editor/src/communication/message.rs

@@ -22,6 +22,8 @@ where
 pub enum Message {
 	#[remain::unsorted]
 	NoOp,
+	#[remain::unsorted]
+	Init,
 	#[child]
 	Broadcast(BroadcastMessage),
 	#[child]